Does Python have a ternary conditional operator

Question

If Python does not have a ternary conditional operator  is it possible to simulate one using other language constructs

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you can do this  -  condition  and  expression 1  or  expression 2    Example - print number 2 and  quot odd quot  or  quot even quot   This would print  quot odd quot  if the number is odd or  quot even quot  if the number is even   The result  -  If condition is true exp 1 is executed else exp 2 is executed  Note  - 0   None   False   emptylist   emptyString evaluates as False  And any data other than 0 evaluates to True  Here s how it works  if the condition  condition  becomes  quot True quot  then   expression 1 will be evaluated but not expression 2   If we  quot and quot  something with 0  zero    the result will always to be fasle  So in the below statement   0 and exp  The expression exp won t be evaluated at all since  quot and quot  with 0 will always evaluate to zero and there is no need to evaluate the expression   This is how the compiler itself works   in all languages  In 1 or exp  the expression exp won t be evaluated at all since  quot or quot  with 1 will always be 1  So it won t bother to evaluate the expression exp since the result will be 1 anyway    compiler optimization methods   But in case of True and exp1 or exp2  The second expression exp2 won t be evaluated since True and exp1 would be True when exp1 isn t false   Similarly in False and exp1 or exp2  The expression exp1 won t be evaluated since False is equivalent to writing 0 and doing  quot and quot  with 0 would be 0 itself but after exp1 since  quot or quot  is used  it will evaluate the expression exp2 after  quot or quot     Note - This kind of branching using  quot or quot  and  quot and quot  can only be used when the expression 1 doesn t have a Truth value of False  or 0 or None or emptylist     or emptystring       since if expression 1 becomes False   then the expression 2 will be evaluated because of the presence  quot or quot  between exp 1 and exp 2  In case you still want to make it work for all the cases regardless of what exp 1 and exp 2 truth values are  do this  -  condition  and   expression 1  or 1  or  expression 2

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More a tip than an answer  don t need to repeat the obvious for the hundreth time   but I sometimes use it as a oneliner shortcut in such constructs   if conditionX      print  yes   else      print  nah       becomes   print  yes   if conditionX else print  nah     Some  many    may frown upon it as unpythonic  even  ruby-ish     but I personally find it more natural - i e  how you d express it normally  plus a bit more visually appealing in large blocks of code

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You might often find  cond and on true or on false   but this lead to problem when on true    0   gt  gt  gt  x   0  gt  gt  gt  print x    0 and 0 or 1  1  gt  gt  gt  x   1  gt  gt  gt  print x    0 and 0 or 1  1   where you would expect for a  normal ternary operator this result   gt  gt  gt  x   0  gt  gt  gt  print 0 if x    0 else 1  0  gt  gt  gt  x   1  gt  gt  gt  print 0 if x    0 else 1  1

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Python has a ternary form for assignments  however there may be even a shorter form that people should be aware of   It s very common to need to assign to a variable one value or another depending on a condition    gt  gt  gt  li1   None  gt  gt  gt  li2    1  2  3   gt  gt  gt    gt  gt  gt  if li1          a   li1     else          a   li2           gt  gt  gt  a  1  2  3      This is the long form for doing such assignments   Below is the ternary form  But this isn t most succinct way - see last example    gt  gt  gt  a   li1 if li1 else li2  gt  gt  gt    gt  gt  gt  a  1  2  3   gt  gt  gt     With Python  you can simply use or for alternative assignments    gt  gt  gt  a   li1 or li2  gt  gt  gt    gt  gt  gt  a  1  2  3   gt  gt  gt     The above works since li1 is None and the interp treats that as False in logic expressions  The interp then moves on and evaluates the second expression  which is not None and it s not an empty list - so it gets assigned to a   This also works with empty lists  For instance  if you want to assign a whichever list has items    gt  gt  gt  li1       gt  gt  gt  li2    1  2  3   gt  gt  gt    gt  gt  gt  a   li1 or li2  gt  gt  gt    gt  gt  gt  a  1  2  3   gt  gt  gt     Knowing this  you can simply such assignments whenever you encounter them  This also works with strings and other iterables  You could assign a whichever string isn t empty    gt  gt  gt  s1       gt  gt  gt  s2    hello world   gt  gt  gt    gt  gt  gt  a   s1 or s2  gt  gt  gt    gt  gt  gt  a  hello world   gt  gt  gt     I always liked the C ternary syntax  but Python takes it a step further   I understand that some may say this isn t a good stylistic choice because it relies on mechanics that aren t immediately apparent to all developers  I personally disagree with that viewpoint  Python is a syntax rich language with lots of idiomatic tricks that aren t immediately apparent to the dabler  But the more you learn and understand the mechanics of the underlying system  the more you appreciate it

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if variable is defined and you want to check if it has value you can just a or b  def test myvar None         shorter than  print myvar if myvar else  no Input      print myvar or  no Input   test   test     test False  test  hello   test   Hello    test True    will output  no Input no Input no Input hello   Hello   True

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Yes  it was added in version 2 5  The expression syntax is  a if condition else b  First condition is evaluated  then exactly one of either a or b is evaluated and returned based on the Boolean value of condition  If condition evaluates to True  then a is evaluated and returned but b is ignored  or else when b is evaluated and returned but a is ignored  This allows short-circuiting because when condition is true only a is evaluated and b is not evaluated at all  but when condition is false only b is evaluated and a is not evaluated at all  For example   gt  gt  gt   true  if True else  false   true   gt  gt  gt   true  if False else  false   false   Note that conditionals are an expression  not a statement  This means you can t use assignment statements or pass or other statements within a conditional expression   gt  gt  gt  pass if False else x   3   File  quot  lt stdin gt  quot   line 1     pass if False else x   3             SyntaxError  invalid syntax  You can  however  use conditional expressions to assign a variable like so  x   a if True else b  Think of the conditional expression as switching between two values  It is very useful when you re in a  one value or another  situation  it but doesn t do much else  If you need to use statements  you have to use a normal if statement instead of a conditional expression   Keep in mind that it s frowned upon by some Pythonistas for several reasons   The order of the arguments is different from those of the classic condition   a   b ternary operator from many other languages  such as C  C    Go  Perl  Ruby  Java  Javascript  etc    which may lead to bugs when people unfamiliar with Python s  quot surprising quot  behaviour use it  they may reverse the argument order   Some find it  quot unwieldy quot   since it goes contrary to the normal flow of thought  thinking of the condition first and then the effects   Stylistic reasons   Although the  inline if  can be really useful  and make your script more concise  it really does complicate your code   If you re having trouble remembering the order  then remember that when read aloud  you  almost  say what you mean  For example  x   4 if b  gt  8 else 9 is read aloud as x will be 4 if b is greater than 8 otherwise 9  Official documentation   Conditional expressions Is there an equivalent of C   s          ternary operator

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For versions prior to 2 5  there s the trick    expression  and  on true  or  on false    It can give wrong results when on true   has a false boolean value 1 Although it does have the benefit of evaluating expressions left to right  which is clearer in my opinion   1  Is there an equivalent of C   s          ternary operator

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You might often find  cond and on true or on false   but this lead to problem when on true    0   gt  gt  gt  x   0  gt  gt  gt  print x    0 and 0 or 1  1  gt  gt  gt  x   1  gt  gt  gt  print x    0 and 0 or 1  1   where you would expect for a  normal ternary operator this result   gt  gt  gt  x   0  gt  gt  gt  print 0 if x    0 else 1  0  gt  gt  gt  x   1  gt  gt  gt  print 0 if x    0 else 1  1

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As already answered  yes there is a ternary operator in python    lt expression 1 gt  if  lt condition gt  else  lt expression 2 gt    Additional information   If  lt expression 1 gt  is the condition you can use Short-cirquit evaluation   a   True b   False    Instead of this  x   a if a else b    You could use Short-cirquit evaluation  x   a or b   PS  Of course  a Short-cirquit evaluation is not a ternary operator but often the ternary is used in cases where the short circuit would be enough

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lt expression 1 gt  if  lt condition gt  else  lt expression 2 gt    a   1 b   2  1 if a  gt  b else -1    Output is -1  1 if a  gt  b else -1 if a  lt  b else 0   Output is -1

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Unfortunately  the   falseValue  trueValue  test    solution doesn t have short-circuit behaviour  thus both falseValue and trueValue are evaluated regardless of the condition  This could be suboptimal or even buggy  i e  both trueValue and falseValue could be methods and have side-effects    One solution to this would be   lambda  falseValue  lambda  trueValue  test       execution delayed until the winner is known      but it introduces inconsistency between callable and non-callable objects  In addition  it doesn t solve the case when using properties   And so the story goes - choosing between 3 mentioned solutions is a trade-off between having the short-circuit feature  using at least  ython 2 5  IMHO not a problem anymore  and not being prone to  trueValue-evaluates-to-false  errors

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A neat way to chain multiple operators   f   lambda x y   greater  if x  gt  y else  less  if y  gt  x else  equal   array     0 0   0 1   1 0   1 1    for a in array    x  y   a 0   a 1    print f x y      Output is      equal      less      greater      equal

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You can index into a tuple    falseValue  trueValue  test    test needs to return True or False  It might be safer to always implement it as    falseValue  trueValue  test    True    or you can use the built-in bool   to assure a Boolean value    falseValue  trueValue  bool  lt expression gt

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For versions prior to 2 5  there s the trick    expression  and  on true  or  on false    It can give wrong results when on true   has a false boolean value 1 Although it does have the benefit of evaluating expressions left to right  which is clearer in my opinion   1  Is there an equivalent of C   s          ternary operator

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Does Python have a ternary conditional operator    Yes  From the grammar file   test  or test   if  or test  else  test    lambdef   The part of interest is   or test   if  or test  else  test    So  a ternary conditional operation is of the form   expression1 if expression2 else expression3   expression3 will be lazily evaluated  that is  evaluated only if expression2 is false in a boolean context   And because of the recursive definition  you can chain them indefinitely  though it may considered bad style    expression1 if expression2 else expression3 if expression4 else expression5   and so on   A note on usage   Note that every if must be followed with an else  People learning list comprehensions and generator expressions may find this to be a difficult lesson to learn - the following will not work  as Python expects a third expression for an else    expression1 if expression2 for element in iterable                              -- need an else here   which raises a SyntaxError  invalid syntax  So the above is either an incomplete piece of logic  perhaps the user expects a no-op in the false condition  or what may be intended is to use expression2 as a filter - notes that the following is legal Python    expression1 for element in iterable if expression2    expression2 works as a filter for the list comprehension  and is not a ternary conditional operator   Alternative syntax for a more narrow case   You may find it somewhat painful to write the following   expression1 if expression1 else expression2   expression1 will have to be evaluated twice with the above usage  It can limit redundancy if it is simply a local variable  However  a common and performant Pythonic idiom for this use-case is to use or s shortcutting behavior   expression1 or expression2   which is equivalent in semantics  Note that some style-guides may limit this usage on the grounds of clarity - it does pack a lot of meaning into very little syntax

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YES  python have a ternary operator  here is the syntax and an example code to demonstrate the same       On true  if  expression  else On false    if the expression evaluates to true then it will pass On true otherwise On false   a  input  Enter the First Number    b  input  Enter the Second Number     print  A is Bigger   if a gt b else print  B is Bigger

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Unfortunately  the   falseValue  trueValue  test    solution doesn t have short-circuit behaviour  thus both falseValue and trueValue are evaluated regardless of the condition  This could be suboptimal or even buggy  i e  both trueValue and falseValue could be methods and have side-effects    One solution to this would be   lambda  falseValue  lambda  trueValue  test       execution delayed until the winner is known      but it introduces inconsistency between callable and non-callable objects  In addition  it doesn t solve the case when using properties   And so the story goes - choosing between 3 mentioned solutions is a trade-off between having the short-circuit feature  using at least  ython 2 5  IMHO not a problem anymore  and not being prone to  trueValue-evaluates-to-false  errors

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Yes  it was added in version 2 5  The expression syntax is  a if condition else b  First condition is evaluated  then exactly one of either a or b is evaluated and returned based on the Boolean value of condition  If condition evaluates to True  then a is evaluated and returned but b is ignored  or else when b is evaluated and returned but a is ignored  This allows short-circuiting because when condition is true only a is evaluated and b is not evaluated at all  but when condition is false only b is evaluated and a is not evaluated at all  For example   gt  gt  gt   true  if True else  false   true   gt  gt  gt   true  if False else  false   false   Note that conditionals are an expression  not a statement  This means you can t use assignment statements or pass or other statements within a conditional expression   gt  gt  gt  pass if False else x   3   File  quot  lt stdin gt  quot   line 1     pass if False else x   3             SyntaxError  invalid syntax  You can  however  use conditional expressions to assign a variable like so  x   a if True else b  Think of the conditional expression as switching between two values  It is very useful when you re in a  one value or another  situation  it but doesn t do much else  If you need to use statements  you have to use a normal if statement instead of a conditional expression   Keep in mind that it s frowned upon by some Pythonistas for several reasons   The order of the arguments is different from those of the classic condition   a   b ternary operator from many other languages  such as C  C    Go  Perl  Ruby  Java  Javascript  etc    which may lead to bugs when people unfamiliar with Python s  quot surprising quot  behaviour use it  they may reverse the argument order   Some find it  quot unwieldy quot   since it goes contrary to the normal flow of thought  thinking of the condition first and then the effects   Stylistic reasons   Although the  inline if  can be really useful  and make your script more concise  it really does complicate your code   If you re having trouble remembering the order  then remember that when read aloud  you  almost  say what you mean  For example  x   4 if b  gt  8 else 9 is read aloud as x will be 4 if b is greater than 8 otherwise 9  Official documentation   Conditional expressions Is there an equivalent of C   s          ternary operator

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You can index into a tuple    falseValue  trueValue  test    test needs to return True or False  It might be safer to always implement it as    falseValue  trueValue  test    True    or you can use the built-in bool   to assure a Boolean value    falseValue  trueValue  bool  lt expression gt

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A neat way to chain multiple operators   f   lambda x y   greater  if x  gt  y else  less  if y  gt  x else  equal   array     0 0   0 1   1 0   1 1    for a in array    x  y   a 0   a 1    print f x y      Output is      equal      less      greater      equal

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is spacial True if gender    Female  else  True if age  gt   65 else False           it can be nested as your need  best of luck

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An operator for a conditional expression in Python was added in 2006 as part of Python Enhancement Proposal 308  Its form differ from common    operator and it s    lt expression1 gt  if  lt condition gt  else  lt expression2 gt    which is equivalent to   if  lt condition gt    lt expression1 gt  else   lt expression2 gt    Here is an example   result   x if a  gt  b else y   Another syntax which can be used  compatible with versions before 2 5    result    lambda y  lambda x  a  gt  b      where operands are lazily evaluated   Another way is by indexing a tuple  which isn t consistent with the conditional operator of most other languages    result    y  x  a  gt  b    or explicitly constructed dictionary   result    True  x  False  y  a  gt  b    Another  less reliable   but simpler method is to use and and or operators   result    a  gt  b  and x or y   however this won t work if x would be False   A possible workaround is to make x and y lists or tuples as in the following   result     a  gt  b  and  x  or  y   0    or   result     a  gt  b  and  x   or  y    0    If you re working with dictionaries  instead of using a ternary conditional  you can take advantage of get key  default   for example   shell   os environ get  SHELL     bin sh     Source     in Python at Wikipedia

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The ternary operator is a way of writing conditional statements in Python  As the name ternary suggests  this Python operator consists of three operands  Syntax  The three operands in a ternary operator include  condition  A boolean expression that evaluates to either true or false  true val  A value to be assigned if the expression is evaluated to true  false val  A value to be assigned if the expression is evaluated to false      var   true val if condition else false val  The variable var on the left-hand side of the    assignment  operator will be assigned  value1 if the booleanExpression evaluates to true  value2 if the booleanExpression evaluates to false  Example        USING TERNARY OPERATOR     to check   6     msg    quot Even quot  if to check 2    0 else  quot Odd quot      print msg          USING USUAL IF-ELSE     msg    quot  quot      if to check 2    0       msg    quot Even quot      else      msg    quot Odd quot      print msg

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YES  python have a ternary operator  here is the syntax and an example code to demonstrate the same       On true  if  expression  else On false    if the expression evaluates to true then it will pass On true otherwise On false   a  input  Enter the First Number    b  input  Enter the Second Number     print  A is Bigger   if a gt b else print  B is Bigger

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Ternary Operator in different programming Languages  Here I just try to show some important difference in ternary operator between a couple of programming languages      Ternary Operator in Javascript   var a   true   1   0    1 var b   false   1   0    0      Ternary Operator in Ruby   a   true   1   0   1 b   false   1   0   0      Ternary operator in Scala   val a   true   1   0   1 val b   false   1   0   0      Ternary operator in R programming   a  lt - if  TRUE  1 else 0   1 b  lt - if  FALSE  1 else 0   0      Ternary operator in Python   a   1 if True else 0   1 b   1 if False else 0   0

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is spacial True if gender    Female  else  True if age  gt   65 else False           it can be nested as your need  best of luck

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you can do this  -  condition  and  expression 1  or  expression 2    Example - print number 2 and  quot odd quot  or  quot even quot   This would print  quot odd quot  if the number is odd or  quot even quot  if the number is even   The result  -  If condition is true exp 1 is executed else exp 2 is executed  Note  - 0   None   False   emptylist   emptyString evaluates as False  And any data other than 0 evaluates to True  Here s how it works  if the condition  condition  becomes  quot True quot  then   expression 1 will be evaluated but not expression 2   If we  quot and quot  something with 0  zero    the result will always to be fasle  So in the below statement   0 and exp  The expression exp won t be evaluated at all since  quot and quot  with 0 will always evaluate to zero and there is no need to evaluate the expression   This is how the compiler itself works   in all languages  In 1 or exp  the expression exp won t be evaluated at all since  quot or quot  with 1 will always be 1  So it won t bother to evaluate the expression exp since the result will be 1 anyway    compiler optimization methods   But in case of True and exp1 or exp2  The second expression exp2 won t be evaluated since True and exp1 would be True when exp1 isn t false   Similarly in False and exp1 or exp2  The expression exp1 won t be evaluated since False is equivalent to writing 0 and doing  quot and quot  with 0 would be 0 itself but after exp1 since  quot or quot  is used  it will evaluate the expression exp2 after  quot or quot     Note - This kind of branching using  quot or quot  and  quot and quot  can only be used when the expression 1 doesn t have a Truth value of False  or 0 or None or emptylist     or emptystring       since if expression 1 becomes False   then the expression 2 will be evaluated because of the presence  quot or quot  between exp 1 and exp 2  In case you still want to make it work for all the cases regardless of what exp 1 and exp 2 truth values are  do this  -  condition  and   expression 1  or 1  or  expression 2

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Python has a ternary form for assignments  however there may be even a shorter form that people should be aware of   It s very common to need to assign to a variable one value or another depending on a condition    gt  gt  gt  li1   None  gt  gt  gt  li2    1  2  3   gt  gt  gt    gt  gt  gt  if li1          a   li1     else          a   li2           gt  gt  gt  a  1  2  3      This is the long form for doing such assignments   Below is the ternary form  But this isn t most succinct way - see last example    gt  gt  gt  a   li1 if li1 else li2  gt  gt  gt    gt  gt  gt  a  1  2  3   gt  gt  gt     With Python  you can simply use or for alternative assignments    gt  gt  gt  a   li1 or li2  gt  gt  gt    gt  gt  gt  a  1  2  3   gt  gt  gt     The above works since li1 is None and the interp treats that as False in logic expressions  The interp then moves on and evaluates the second expression  which is not None and it s not an empty list - so it gets assigned to a   This also works with empty lists  For instance  if you want to assign a whichever list has items    gt  gt  gt  li1       gt  gt  gt  li2    1  2  3   gt  gt  gt    gt  gt  gt  a   li1 or li2  gt  gt  gt    gt  gt  gt  a  1  2  3   gt  gt  gt     Knowing this  you can simply such assignments whenever you encounter them  This also works with strings and other iterables  You could assign a whichever string isn t empty    gt  gt  gt  s1       gt  gt  gt  s2    hello world   gt  gt  gt    gt  gt  gt  a   s1 or s2  gt  gt  gt    gt  gt  gt  a  hello world   gt  gt  gt     I always liked the C ternary syntax  but Python takes it a step further   I understand that some may say this isn t a good stylistic choice because it relies on mechanics that aren t immediately apparent to all developers  I personally disagree with that viewpoint  Python is a syntax rich language with lots of idiomatic tricks that aren t immediately apparent to the dabler  But the more you learn and understand the mechanics of the underlying system  the more you appreciate it

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For versions prior to 2 5  there s the trick    expression  and  on true  or  on false    It can give wrong results when on true   has a false boolean value 1 Although it does have the benefit of evaluating expressions left to right  which is clearer in my opinion   1  Is there an equivalent of C   s          ternary operator

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Ternary conditional operator simply allows testing a condition in a single line replacing the multiline if-else making the code compact   Syntax        on true  if  expression  else  on false     1- Simple Method to use ternary operator     Program to demonstrate conditional operator a  b   10  20   Copy value of a in min if a  lt  b else copy b min   a if a  lt  b else b print min     Output  10   2- Direct Method of using tuples  Dictionary  and lambda     Python program to demonstrate ternary operator a  b   10  20   Use tuple for selecting an item print   b  a   a  lt  b      Use Dictionary for selecting an item print  True  a  False  b   a  lt  b     lamda is more efficient than above two methods   because in lambda  we are assure that   only one expression will be evaluated unlike in   tuple and Dictionary print  lambda  b  lambda  a  a  lt  b       in output you should see three 10   3- Ternary operator can be written as nested if-else     Python program to demonstrate nested ternary operator a  b   10  20 print   Both a and b are equal  if a    b else  a is greater than b          if a  gt  b else  b is greater than a     Above approach can be written as     Python program to demonstrate nested ternary operator a  b   10  20 if a    b      if a  gt  b          print  a is greater than b       else          print  b is greater than a   else      print  Both a and b are equal      Output  b is greater than a

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Simulating the python ternary operator   For example  a  b  x  y   1  2   a greather than b    b greater than a  result    lambda y  lambda x  a  gt  b      output    b greater than a

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You can index into a tuple    falseValue  trueValue  test    test needs to return True or False  It might be safer to always implement it as    falseValue  trueValue  test    True    or you can use the built-in bool   to assure a Boolean value    falseValue  trueValue  bool  lt expression gt

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For Python 2 5 and newer there is a specific syntax    on true  if  cond  else  on false    In older Pythons a ternary operator is not implemented but it s possible to simulate it   cond and on true or on false   Though  there is a potential problem  which if cond evaluates to True and on true evaluates to False then on false is returned instead of on true  If you want this behavior the method is OK  otherwise use this    True  on true  False  on false  cond is True    is True  not    True   which can be wrapped by   def q cond  on true  on false      return  True  on true  False  on false  cond is True    and used this way   q cond  on true  on false    It is compatible with all Python versions

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if variable is defined and you want to check if it has value you can just a or b  def test myvar None         shorter than  print myvar if myvar else  no Input      print myvar or  no Input   test   test     test False  test  hello   test   Hello    test True    will output  no Input no Input no Input hello   Hello   True

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For versions prior to 2 5  there s the trick    expression  and  on true  or  on false    It can give wrong results when on true   has a false boolean value 1 Although it does have the benefit of evaluating expressions left to right  which is clearer in my opinion   1  Is there an equivalent of C   s          ternary operator

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From the documentation      Conditional expressions  sometimes called a    ternary operator     have the lowest priority of all Python operations       The expression x if C else y first evaluates the condition  C  not x   if C is true  x is evaluated and its value is returned  otherwise  y is evaluated and its value is returned       See PEP 308 for more details about conditional expressions    New since version 2 5

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Yes  it was added in version 2 5  The expression syntax is  a if condition else b  First condition is evaluated  then exactly one of either a or b is evaluated and returned based on the Boolean value of condition  If condition evaluates to True  then a is evaluated and returned but b is ignored  or else when b is evaluated and returned but a is ignored  This allows short-circuiting because when condition is true only a is evaluated and b is not evaluated at all  but when condition is false only b is evaluated and a is not evaluated at all  For example   gt  gt  gt   true  if True else  false   true   gt  gt  gt   true  if False else  false   false   Note that conditionals are an expression  not a statement  This means you can t use assignment statements or pass or other statements within a conditional expression   gt  gt  gt  pass if False else x   3   File  quot  lt stdin gt  quot   line 1     pass if False else x   3             SyntaxError  invalid syntax  You can  however  use conditional expressions to assign a variable like so  x   a if True else b  Think of the conditional expression as switching between two values  It is very useful when you re in a  one value or another  situation  it but doesn t do much else  If you need to use statements  you have to use a normal if statement instead of a conditional expression   Keep in mind that it s frowned upon by some Pythonistas for several reasons   The order of the arguments is different from those of the classic condition   a   b ternary operator from many other languages  such as C  C    Go  Perl  Ruby  Java  Javascript  etc    which may lead to bugs when people unfamiliar with Python s  quot surprising quot  behaviour use it  they may reverse the argument order   Some find it  quot unwieldy quot   since it goes contrary to the normal flow of thought  thinking of the condition first and then the effects   Stylistic reasons   Although the  inline if  can be really useful  and make your script more concise  it really does complicate your code   If you re having trouble remembering the order  then remember that when read aloud  you  almost  say what you mean  For example  x   4 if b  gt  8 else 9 is read aloud as x will be 4 if b is greater than 8 otherwise 9  Official documentation   Conditional expressions Is there an equivalent of C   s          ternary operator

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Vinko Vrsalovic s answer is good enough  There is only one more thing   Note that conditionals are an expression  not a statement  This means you can t use assignment statements or pass or other statements within a conditional expression  Walrus operator in Python 3 8 After that walrus operator was introduced in Python 3 8  there is something changed   a    3  if True else  b    5   gives a   3 and b is not defined   a    3  if False else  b    5   gives a is not defined and b   5  and c    a    3  if False else  b    5   gives c   5  a is not defined and b   5  Even if this may be ugly  assignments can be done inside conditional expressions after Python 3 8  Anyway  it is still better to use normal if statement instead in this case

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For Python 2 5 and newer there is a specific syntax    on true  if  cond  else  on false    In older Pythons a ternary operator is not implemented but it s possible to simulate it   cond and on true or on false   Though  there is a potential problem  which if cond evaluates to True and on true evaluates to False then on false is returned instead of on true  If you want this behavior the method is OK  otherwise use this    True  on true  False  on false  cond is True    is True  not    True   which can be wrapped by   def q cond  on true  on false      return  True  on true  False  on false  cond is True    and used this way   q cond  on true  on false    It is compatible with all Python versions

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Vinko Vrsalovic s answer is good enough  There is only one more thing   Note that conditionals are an expression  not a statement  This means you can t use assignment statements or pass or other statements within a conditional expression  Walrus operator in Python 3 8 After that walrus operator was introduced in Python 3 8  there is something changed   a    3  if True else  b    5   gives a   3 and b is not defined   a    3  if False else  b    5   gives a is not defined and b   5  and c    a    3  if False else  b    5   gives c   5  a is not defined and b   5  Even if this may be ugly  assignments can be done inside conditional expressions after Python 3 8  Anyway  it is still better to use normal if statement instead in this case

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One of the alternatives to Python s conditional expression   yes  if boolean else  no    is the following    True  yes   False  no   boolean    which has the following nice extension    True  yes   False  no   None  maybe   boolean or none    The shortest alternative remains     no    yes   boolean    but there is no alternative to  yes   if boolean else no     if you want to avoid the evaluation of yes   and no    because in   no    yes    boolean     bad   both no   and yes   are evaluated

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lt expression 1 gt  if  lt condition gt  else  lt expression 2 gt    a   1 b   2  1 if a  gt  b else -1    Output is -1  1 if a  gt  b else -1 if a  lt  b else 0   Output is -1

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Many programming languages derived from C usually have the following syntax of ternary conditional operator    lt condition gt     lt expression1 gt     lt expression2 gt       At first  the Python Benevolent Dictator For Life  I mean Guido van Rossum  of course  rejected it  as non-Pythonic style   since it s quite hard to understand for people not used to C language  Also  the colon sign   already has many uses in Python  After PEP 308 was approved  Python finally received its own shortcut conditional expression  what we use now      lt expression1 gt  if  lt condition gt  else  lt expression2 gt    So  firstly it evaluates the condition  If it returns True  expression1 will be evaluated to give the result  otherwise expression2 will be evaluated  Due to Lazy Evaluation mechanics     only one expression will be executed   Here are some examples  conditions will be evaluated from left to right    pressure   10 print  High  if pressure  lt  20 else  Critical      Result is  High    Ternary operators can be chained in series        pressure   5 print  Normal  if pressure  lt  10 else  High  if pressure  lt  20 else  Critical      Result is  Normal    The following one is the same as previous one   pressure   5  if pressure  lt  20      if pressure  lt  10          print  Normal       else          print  High   else      print  Critical      Result is  Normal    Hope this helps

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Does Python have a ternary conditional operator    Yes  From the grammar file   test  or test   if  or test  else  test    lambdef   The part of interest is   or test   if  or test  else  test    So  a ternary conditional operation is of the form   expression1 if expression2 else expression3   expression3 will be lazily evaluated  that is  evaluated only if expression2 is false in a boolean context   And because of the recursive definition  you can chain them indefinitely  though it may considered bad style    expression1 if expression2 else expression3 if expression4 else expression5   and so on   A note on usage   Note that every if must be followed with an else  People learning list comprehensions and generator expressions may find this to be a difficult lesson to learn - the following will not work  as Python expects a third expression for an else    expression1 if expression2 for element in iterable                              -- need an else here   which raises a SyntaxError  invalid syntax  So the above is either an incomplete piece of logic  perhaps the user expects a no-op in the false condition  or what may be intended is to use expression2 as a filter - notes that the following is legal Python    expression1 for element in iterable if expression2    expression2 works as a filter for the list comprehension  and is not a ternary conditional operator   Alternative syntax for a more narrow case   You may find it somewhat painful to write the following   expression1 if expression1 else expression2   expression1 will have to be evaluated twice with the above usage  It can limit redundancy if it is simply a local variable  However  a common and performant Pythonic idiom for this use-case is to use or s shortcutting behavior   expression1 or expression2   which is equivalent in semantics  Note that some style-guides may limit this usage on the grounds of clarity - it does pack a lot of meaning into very little syntax

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One of the alternatives to Python s conditional expression   yes  if boolean else  no    is the following    True  yes   False  no   boolean    which has the following nice extension    True  yes   False  no   None  maybe   boolean or none    The shortest alternative remains     no    yes   boolean    but there is no alternative to  yes   if boolean else no     if you want to avoid the evaluation of yes   and no    because in   no    yes    boolean     bad   both no   and yes   are evaluated

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Ternary conditional operator simply allows testing a condition in a single line replacing the multiline if-else making the code compact   Syntax        on true  if  expression  else  on false     1- Simple Method to use ternary operator     Program to demonstrate conditional operator a  b   10  20   Copy value of a in min if a  lt  b else copy b min   a if a  lt  b else b print min     Output  10   2- Direct Method of using tuples  Dictionary  and lambda     Python program to demonstrate ternary operator a  b   10  20   Use tuple for selecting an item print   b  a   a  lt  b      Use Dictionary for selecting an item print  True  a  False  b   a  lt  b     lamda is more efficient than above two methods   because in lambda  we are assure that   only one expression will be evaluated unlike in   tuple and Dictionary print  lambda  b  lambda  a  a  lt  b       in output you should see three 10   3- Ternary operator can be written as nested if-else     Python program to demonstrate nested ternary operator a  b   10  20 print   Both a and b are equal  if a    b else  a is greater than b          if a  gt  b else  b is greater than a     Above approach can be written as     Python program to demonstrate nested ternary operator a  b   10  20 if a    b      if a  gt  b          print  a is greater than b       else          print  b is greater than a   else      print  Both a and b are equal      Output  b is greater than a

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Yes  it was added in version 2 5  The expression syntax is  a if condition else b  First condition is evaluated  then exactly one of either a or b is evaluated and returned based on the Boolean value of condition  If condition evaluates to True  then a is evaluated and returned but b is ignored  or else when b is evaluated and returned but a is ignored  This allows short-circuiting because when condition is true only a is evaluated and b is not evaluated at all  but when condition is false only b is evaluated and a is not evaluated at all  For example   gt  gt  gt   true  if True else  false   true   gt  gt  gt   true  if False else  false   false   Note that conditionals are an expression  not a statement  This means you can t use assignment statements or pass or other statements within a conditional expression   gt  gt  gt  pass if False else x   3   File  quot  lt stdin gt  quot   line 1     pass if False else x   3             SyntaxError  invalid syntax  You can  however  use conditional expressions to assign a variable like so  x   a if True else b  Think of the conditional expression as switching between two values  It is very useful when you re in a  one value or another  situation  it but doesn t do much else  If you need to use statements  you have to use a normal if statement instead of a conditional expression   Keep in mind that it s frowned upon by some Pythonistas for several reasons   The order of the arguments is different from those of the classic condition   a   b ternary operator from many other languages  such as C  C    Go  Perl  Ruby  Java  Javascript  etc    which may lead to bugs when people unfamiliar with Python s  quot surprising quot  behaviour use it  they may reverse the argument order   Some find it  quot unwieldy quot   since it goes contrary to the normal flow of thought  thinking of the condition first and then the effects   Stylistic reasons   Although the  inline if  can be really useful  and make your script more concise  it really does complicate your code   If you re having trouble remembering the order  then remember that when read aloud  you  almost  say what you mean  For example  x   4 if b  gt  8 else 9 is read aloud as x will be 4 if b is greater than 8 otherwise 9  Official documentation   Conditional expressions Is there an equivalent of C   s          ternary operator

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From the documentation      Conditional expressions  sometimes called a    ternary operator     have the lowest priority of all Python operations       The expression x if C else y first evaluates the condition  C  not x   if C is true  x is evaluated and its value is returned  otherwise  y is evaluated and its value is returned       See PEP 308 for more details about conditional expressions    New since version 2 5

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Other answers correctly talk about the Python ternary operator  I would like to complement by mentioning a scenario for which the ternary operator is often used but for which there is a better idiom  This is the scenario of using a default value  Suppose we want to use option value with a default value if it is not set  run algorithm option value if option value is not None else 10   or  if option value is never set to a falsy value  0   quot  quot   etc   simply run algorithm option value if option value else 10   However  in this case an ever better solution is simply to write run algorithm option value or 10

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The ternary operator is a way of writing conditional statements in Python  As the name ternary suggests  this Python operator consists of three operands  Syntax  The three operands in a ternary operator include  condition  A boolean expression that evaluates to either true or false  true val  A value to be assigned if the expression is evaluated to true  false val  A value to be assigned if the expression is evaluated to false      var   true val if condition else false val  The variable var on the left-hand side of the    assignment  operator will be assigned  value1 if the booleanExpression evaluates to true  value2 if the booleanExpression evaluates to false  Example        USING TERNARY OPERATOR     to check   6     msg    quot Even quot  if to check 2    0 else  quot Odd quot      print msg          USING USUAL IF-ELSE     msg    quot  quot      if to check 2    0       msg    quot Even quot      else      msg    quot Odd quot      print msg

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As already answered  yes there is a ternary operator in python    lt expression 1 gt  if  lt condition gt  else  lt expression 2 gt    Additional information   If  lt expression 1 gt  is the condition you can use Short-cirquit evaluation   a   True b   False    Instead of this  x   a if a else b    You could use Short-cirquit evaluation  x   a or b   PS  Of course  a Short-cirquit evaluation is not a ternary operator but often the ternary is used in cases where the short circuit would be enough

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a if condition else b   Just memorize this pyramid if you have trouble remembering        condition   if           else a                   b

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Other answers correctly talk about the Python ternary operator  I would like to complement by mentioning a scenario for which the ternary operator is often used but for which there is a better idiom  This is the scenario of using a default value  Suppose we want to use option value with a default value if it is not set  run algorithm option value if option value is not None else 10   or  if option value is never set to a falsy value  0   quot  quot   etc   simply run algorithm option value if option value else 10   However  in this case an ever better solution is simply to write run algorithm option value or 10

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From the documentation      Conditional expressions  sometimes called a    ternary operator     have the lowest priority of all Python operations       The expression x if C else y first evaluates the condition  C  not x   if C is true  x is evaluated and its value is returned  otherwise  y is evaluated and its value is returned       See PEP 308 for more details about conditional expressions    New since version 2 5

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More a tip than an answer  don t need to repeat the obvious for the hundreth time   but I sometimes use it as a oneliner shortcut in such constructs   if conditionX      print  yes   else      print  nah       becomes   print  yes   if conditionX else print  nah     Some  many    may frown upon it as unpythonic  even  ruby-ish     but I personally find it more natural - i e  how you d express it normally  plus a bit more visually appealing in large blocks of code

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a if condition else b   Just memorize this pyramid if you have trouble remembering        condition   if           else a                   b

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Simulating the python ternary operator   For example  a  b  x  y   1  2   a greather than b    b greater than a  result    lambda y  lambda x  a  gt  b      output    b greater than a

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An operator for a conditional expression in Python was added in 2006 as part of Python Enhancement Proposal 308  Its form differ from common    operator and it s    lt expression1 gt  if  lt condition gt  else  lt expression2 gt    which is equivalent to   if  lt condition gt    lt expression1 gt  else   lt expression2 gt    Here is an example   result   x if a  gt  b else y   Another syntax which can be used  compatible with versions before 2 5    result    lambda y  lambda x  a  gt  b      where operands are lazily evaluated   Another way is by indexing a tuple  which isn t consistent with the conditional operator of most other languages    result    y  x  a  gt  b    or explicitly constructed dictionary   result    True  x  False  y  a  gt  b    Another  less reliable   but simpler method is to use and and or operators   result    a  gt  b  and x or y   however this won t work if x would be False   A possible workaround is to make x and y lists or tuples as in the following   result     a  gt  b  and  x  or  y   0    or   result     a  gt  b  and  x   or  y    0    If you re working with dictionaries  instead of using a ternary conditional  you can take advantage of get key  default   for example   shell   os environ get  SHELL     bin sh     Source     in Python at Wikipedia

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You can index into a tuple    falseValue  trueValue  test    test needs to return True or False  It might be safer to always implement it as    falseValue  trueValue  test    True    or you can use the built-in bool   to assure a Boolean value    falseValue  trueValue  bool  lt expression gt

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I find cumbersome the default python syntax val   a if cond else b  so sometimes I do this   iif   lambda  cond  a  b   a if cond else b   so I can then use it like  val   iif cond  a  b    Of course  it has the downside of always evaluating both sides  a and b   but the syntax it s way clearer to me

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Ternary Operator in different programming Languages  Here I just try to show some important difference in ternary operator between a couple of programming languages      Ternary Operator in Javascript   var a   true   1   0    1 var b   false   1   0    0      Ternary Operator in Ruby   a   true   1   0   1 b   false   1   0   0      Ternary operator in Scala   val a   true   1   0   1 val b   false   1   0   0      Ternary operator in R programming   a  lt - if  TRUE  1 else 0   1 b  lt - if  FALSE  1 else 0   0      Ternary operator in Python   a   1 if True else 0   1 b   1 if False else 0   0

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From the documentation      Conditional expressions  sometimes called a    ternary operator     have the lowest priority of all Python operations       The expression x if C else y first evaluates the condition  C  not x   if C is true  x is evaluated and its value is returned  otherwise  y is evaluated and its value is returned       See PEP 308 for more details about conditional expressions    New since version 2 5

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I find cumbersome the default python syntax val   a if cond else b  so sometimes I do this   iif   lambda  cond  a  b   a if cond else b   so I can then use it like  val   iif cond  a  b    Of course  it has the downside of always evaluating both sides  a and b   but the syntax it s way clearer to me

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Many programming languages derived from C usually have the following syntax of ternary conditional operator    lt condition gt     lt expression1 gt     lt expression2 gt       At first  the Python Benevolent Dictator For Life  I mean Guido van Rossum  of course  rejected it  as non-Pythonic style   since it s quite hard to understand for people not used to C language  Also  the colon sign   already has many uses in Python  After PEP 308 was approved  Python finally received its own shortcut conditional expression  what we use now      lt expression1 gt  if  lt condition gt  else  lt expression2 gt    So  firstly it evaluates the condition  If it returns True  expression1 will be evaluated to give the result  otherwise expression2 will be evaluated  Due to Lazy Evaluation mechanics     only one expression will be executed   Here are some examples  conditions will be evaluated from left to right    pressure   10 print  High  if pressure  lt  20 else  Critical      Result is  High    Ternary operators can be chained in series        pressure   5 print  Normal  if pressure  lt  10 else  High  if pressure  lt  20 else  Critical      Result is  Normal    The following one is the same as previous one   pressure   5  if pressure  lt  20      if pressure  lt  10          print  Normal       else          print  High   else      print  Critical      Result is  Normal    Hope this helps

[python] Does Python have a ternary conditional operator?

`[condition] and [expression_1] or [expression_2] ;`

`print(number%2 and "odd" or "even")`

The result :- If condition is true exp_1 is executed else exp_2 is executed.

Here's how it works:

`[condition] and ([expression_1] or 1) or [expression_2] ;`

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