Is there a way to perform if in python s lambda

Question

In python 2 6  I want to do   f   lambda x  if x  2 print x else raise Exception   f 2   should print  2  f 3   should throw an exception   This clearly isn t the syntax  Is it possible to perform an if in lambda and if so how to do it   thanks

User · Answer

the solution for the given scenerio is  f   lambda x   x if x    2 else print  quot number is not 2 quot   f 30     number is not 2 f 2     2

User · Answer

I think this is what you were looking for  gt  gt  gt  f   lambda x   print x  if x  2 else print  quot ERROR quot    gt  gt  gt  f 23  ERROR  gt  gt  gt  f 2  2  gt  gt  gt

User · Answer

Probably the worst python line I ve written so far    f   lambda x  sys stdout write   2 n    2  x  2 -2     If x    2 you print    if x    2 you raise

User · Answer

You can easily raise an exception in a lambda  if that s what you really want to do   def Raise exception       raise exception x   lambda y  1 if y  lt  2 else Raise ValueError  invalid value      Is this a good idea   My instinct in general is to leave the error reporting out of lambdas  let it have a value of None and raise the error in the caller   I don t think this is inherently evil  though--I consider the  y if x else z  syntax itself worse--just make sure you re not trying to stuff too much into a lambda body

User · Answer

Try it   is even   lambda x  True if x   2    0 else False print is even 10   print is even 11     Out   True False

User · Answer

An easy way to perform an if in lambda is by using list comprehension    You can t raise an exception in lambda  but this is a way in Python 3 x to do something close to your example   f   lambda x  print x  if x  2 else print  exception     Another example   return 1 if M otherwise 0  f   lambda x  1 if x   M  else 0

User · Answer

Lambdas in Python are fairly restrictive with regard to what you re allowed to use  Specifically  you can t have any keywords  except for operators like and  not  or  etc  in their body   So  there s no way you could use a lambda for your example  because you can t use raise   but if you re willing to concede on that    You could use   f   lambda x  x    2 and x or None

User · Answer

note you can use several else   if statements in your lambda definition   f   lambda x  1 if x gt 0 else 0 if x   0 else -1

User · Answer

The syntax you re looking for   lambda x  True if x   2    0 else False   But you can t use print or raise in a lambda

User · Answer

Following sample code works for me  Not sure if it directly relates to this question  but hope it helps in some other cases   a      join map lambda x  str x 2  if x 2  0 else     range 10

User · Answer

This snippet should help you   x   lambda age   Older  if age  gt  30 else  Younger   print x 40

User · Answer

what you need exactly is  def fun        raise Exception   f   lambda x print x if x  2 else fun     now call the function the way you need  f 2  f 3

User · Answer

You can also use Logical Operators to have something like a Conditional  func   lambda element   expression and DoSomething  or DoSomethingIfExpressionIsFalse   You can see more about Logical Operators here

User · Answer

why don t you just define a function   def f x       if x    2          print x      else          raise ValueError   there really is no justification to use lambda in this case

User · Answer

If you still want to print you can import future module  from   future   import print function  f   lambda x  print x  if x 2    0 else False

User · Answer

Hope this will help a little you can resolve this problem in the following way f   lambda x   x  2     if f 3     print  quot do logic quot   else    print  quot another logic quot

[python] Is there a way to perform "if" in python's lambda

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