How to determine a Python variable s type

Question

How do I see the type of a variable whether it is unsigned 32 bit  signed 16 bit  etc    How do I view it

User · Answer

Use the type   builtin function    gt  gt  gt  i   123  gt  gt  gt  type i   lt type  int  gt   gt  gt  gt  type i  is int True  gt  gt  gt  i   123 456  gt  gt  gt  type i   lt type  float  gt   gt  gt  gt  type i  is float True   To check if a variable is of a given type  use isinstance    gt  gt  gt  i   123  gt  gt  gt  isinstance i  int  True  gt  gt  gt  isinstance i   float  str  set  dict   False   Note that Python doesn t have the same types as C C    which appears to be your question

User · Answer

The question is somewhat ambiguous -- I m not sure what you mean by  view   If you are trying to query the type of a native Python object   atzz s answer will steer you in the right direction   However  if you are trying to generate Python objects that have the semantics of primitive C-types   such as uint32 t  int16 t   use the struct module  You can determine the number of bits in a given C-type primitive thusly    gt  gt  gt  struct calcsize  c     char 1  gt  gt  gt  struct calcsize  h     short 2  gt  gt  gt  struct calcsize  i     int 4  gt  gt  gt  struct calcsize  l     long 4   This is also reflected in the array module  which can make arrays of these lower-level types    gt  gt  gt  array array  c   itemsize   char 1   The maximum integer supported  Python 2 s int  is given by sys maxint    gt  gt  gt  import sys  math  gt  gt  gt  math ceil math log sys maxint  2     1   Signedness 32 0   There is also sys getsizeof  which returns the actual size of the Python object in residual memory    gt  gt  gt  a   5  gt  gt  gt  sys getsizeof a    Residual memory  12   For float data and precision data  use sys float info    gt  gt  gt  sys float info sys floatinfo max 1 7976931348623157e 308  max exp 1024  max 10 exp 308  min 2 2250738585072014e-308  min exp -1021  min 10 exp -307  dig 15  mant dig 53  epsilon 2 2204460492503131e-16  radix 2  rounds 1

User · Answer

For python2 x  use   print type variable name    For python3 x  use   print type variable name

User · Answer

It really depends on what level you mean  In Python 2 x  there are two integer types  int  constrained to sys maxint  and long  unlimited precision   for historical reasons  In Python code  this shouldn t make a bit of difference because the interpreter automatically converts to long when a number is too large  If you want to know about the actual data types used in the underlying interpreter  that s implementation dependent   CPython s are located in Objects intobject c and Objects longobject c   To find out about the systems types look at cdleary answer for using the struct module

User · Answer

The question is somewhat ambiguous -- I m not sure what you mean by  view   If you are trying to query the type of a native Python object   atzz s answer will steer you in the right direction   However  if you are trying to generate Python objects that have the semantics of primitive C-types   such as uint32 t  int16 t   use the struct module  You can determine the number of bits in a given C-type primitive thusly    gt  gt  gt  struct calcsize  c     char 1  gt  gt  gt  struct calcsize  h     short 2  gt  gt  gt  struct calcsize  i     int 4  gt  gt  gt  struct calcsize  l     long 4   This is also reflected in the array module  which can make arrays of these lower-level types    gt  gt  gt  array array  c   itemsize   char 1   The maximum integer supported  Python 2 s int  is given by sys maxint    gt  gt  gt  import sys  math  gt  gt  gt  math ceil math log sys maxint  2     1   Signedness 32 0   There is also sys getsizeof  which returns the actual size of the Python object in residual memory    gt  gt  gt  a   5  gt  gt  gt  sys getsizeof a    Residual memory  12   For float data and precision data  use sys float info    gt  gt  gt  sys float info sys floatinfo max 1 7976931348623157e 308  max exp 1024  max 10 exp 308  min 2 2250738585072014e-308  min exp -1021  min 10 exp -307  dig 15  mant dig 53  epsilon 2 2204460492503131e-16  radix 2  rounds 1

User · Answer

Just do not do it  Asking for something s type is wrong in itself  Instead use polymorphism  Find or if necessary define by yourself the method that does what you want for any possible type of input and just call it without asking about anything  If you need to work with built-in types or types defined by a third-party library  you can always inherit from them and use your own derivatives instead  Or you can wrap them inside your own class  This is the object-oriented way to resolve such problems   If you insist on checking exact type and placing some dirty ifs here and there  you can use   class   property or type function to do it  but soon you will find yourself updating all these ifs with additional cases every two or three commits  Doing it the OO way prevents that and lets you only define a new class for a new type of input instead

User · Answer

Use the type   builtin function    gt  gt  gt  i   123  gt  gt  gt  type i   lt type  int  gt   gt  gt  gt  type i  is int True  gt  gt  gt  i   123 456  gt  gt  gt  type i   lt type  float  gt   gt  gt  gt  type i  is float True   To check if a variable is of a given type  use isinstance    gt  gt  gt  i   123  gt  gt  gt  isinstance i  int  True  gt  gt  gt  isinstance i   float  str  set  dict   False   Note that Python doesn t have the same types as C C    which appears to be your question

User · Answer

Use the type   builtin function    gt  gt  gt  i   123  gt  gt  gt  type i   lt type  int  gt   gt  gt  gt  type i  is int True  gt  gt  gt  i   123 456  gt  gt  gt  type i   lt type  float  gt   gt  gt  gt  type i  is float True   To check if a variable is of a given type  use isinstance    gt  gt  gt  i   123  gt  gt  gt  isinstance i  int  True  gt  gt  gt  isinstance i   float  str  set  dict   False   Note that Python doesn t have the same types as C C    which appears to be your question

User · Answer

Do you mean in Python or using ctypes   In the first case  you simply cannot - because Python does not have signed unsigned  16 32 bit integers   In the second case  you can use type      gt  gt  gt  import ctypes  gt  gt  gt  a   ctypes c uint     unsigned int  gt  gt  gt  type a   lt class  ctypes c ulong  gt    For more reference on ctypes  an its type  see the official documentation

User · Answer

You may be looking for the type   built-in function   See the examples below  but there s no  unsigned  type in Python just like Java   Positive integer    gt  gt  gt  v   10  gt  gt  gt  type v   lt type  int  gt    Large positive integer    gt  gt  gt  v   100000000000000  gt  gt  gt  type v   lt type  long  gt    Negative integer    gt  gt  gt  v   -10  gt  gt  gt  type v   lt type  int  gt    Literal sequence of characters    gt  gt  gt  v    hi   gt  gt  gt  type v   lt type  str  gt    Floating point integer    gt  gt  gt  v   3 14159  gt  gt  gt  type v   lt type  float  gt

User · Answer

print type variable name    I also highly recommend the IPython interactive interpreter when dealing with questions like this  It lets you type variable name  and will return a whole list of information about the object including the type and the doc string for the type   e g   In  9   var   123  In  10   var  Type        int Base Class   lt type  int  gt  String Form     123 Namespace   Interactive Docstring      int x   base   - gt  integer   Convert a string or number to an integer  if possible   A floating point argument will be truncated towards zero  this does not include a string representation of a floating point number    When converting a string  use the optional base   It is an error to supply a base when converting a         non-string  If the argument is outside the integer range a long object         will be returned instead

User · Answer

You may be looking for the type   built-in function   See the examples below  but there s no  unsigned  type in Python just like Java   Positive integer    gt  gt  gt  v   10  gt  gt  gt  type v   lt type  int  gt    Large positive integer    gt  gt  gt  v   100000000000000  gt  gt  gt  type v   lt type  long  gt    Negative integer    gt  gt  gt  v   -10  gt  gt  gt  type v   lt type  int  gt    Literal sequence of characters    gt  gt  gt  v    hi   gt  gt  gt  type v   lt type  str  gt    Floating point integer    gt  gt  gt  v   3 14159  gt  gt  gt  type v   lt type  float  gt

User · Answer

print type variable name    I also highly recommend the IPython interactive interpreter when dealing with questions like this  It lets you type variable name  and will return a whole list of information about the object including the type and the doc string for the type   e g   In  9   var   123  In  10   var  Type        int Base Class   lt type  int  gt  String Form     123 Namespace   Interactive Docstring      int x   base   - gt  integer   Convert a string or number to an integer  if possible   A floating point argument will be truncated towards zero  this does not include a string representation of a floating point number    When converting a string  use the optional base   It is an error to supply a base when converting a         non-string  If the argument is outside the integer range a long object         will be returned instead

User · Answer

Do you mean in Python or using ctypes   In the first case  you simply cannot - because Python does not have signed unsigned  16 32 bit integers   In the second case  you can use type      gt  gt  gt  import ctypes  gt  gt  gt  a   ctypes c uint     unsigned int  gt  gt  gt  type a   lt class  ctypes c ulong  gt    For more reference on ctypes  an its type  see the official documentation

User · Answer

Do you mean in Python or using ctypes   In the first case  you simply cannot - because Python does not have signed unsigned  16 32 bit integers   In the second case  you can use type      gt  gt  gt  import ctypes  gt  gt  gt  a   ctypes c uint     unsigned int  gt  gt  gt  type a   lt class  ctypes c ulong  gt    For more reference on ctypes  an its type  see the official documentation

User · Answer

It may be little irrelevant  but you can check types of an object with isinstance object  type  as mentioned here

User · Answer

It is so simple  You do it like this   print type variable name

User · Answer

print type variable name    I also highly recommend the IPython interactive interpreter when dealing with questions like this  It lets you type variable name  and will return a whole list of information about the object including the type and the doc string for the type   e g   In  9   var   123  In  10   var  Type        int Base Class   lt type  int  gt  String Form     123 Namespace   Interactive Docstring      int x   base   - gt  integer   Convert a string or number to an integer  if possible   A floating point argument will be truncated towards zero  this does not include a string representation of a floating point number    When converting a string  use the optional base   It is an error to supply a base when converting a         non-string  If the argument is outside the integer range a long object         will be returned instead

User · Answer

The question is somewhat ambiguous -- I m not sure what you mean by  view   If you are trying to query the type of a native Python object   atzz s answer will steer you in the right direction   However  if you are trying to generate Python objects that have the semantics of primitive C-types   such as uint32 t  int16 t   use the struct module  You can determine the number of bits in a given C-type primitive thusly    gt  gt  gt  struct calcsize  c     char 1  gt  gt  gt  struct calcsize  h     short 2  gt  gt  gt  struct calcsize  i     int 4  gt  gt  gt  struct calcsize  l     long 4   This is also reflected in the array module  which can make arrays of these lower-level types    gt  gt  gt  array array  c   itemsize   char 1   The maximum integer supported  Python 2 s int  is given by sys maxint    gt  gt  gt  import sys  math  gt  gt  gt  math ceil math log sys maxint  2     1   Signedness 32 0   There is also sys getsizeof  which returns the actual size of the Python object in residual memory    gt  gt  gt  a   5  gt  gt  gt  sys getsizeof a    Residual memory  12   For float data and precision data  use sys float info    gt  gt  gt  sys float info sys floatinfo max 1 7976931348623157e 308  max exp 1024  max 10 exp 308  min 2 2250738585072014e-308  min exp -1021  min 10 exp -307  dig 15  mant dig 53  epsilon 2 2204460492503131e-16  radix 2  rounds 1

User · Answer

One more way using   class      gt  gt  gt  a    1  2  3  4   gt  gt  gt  a   class    lt type  list  gt   gt  gt  gt  b     key1    val1    gt  gt  gt  b   class    lt type  dict  gt   gt  gt  gt  c   12  gt  gt  gt  c   class    lt type  int  gt

User · Answer

print type variable name    I also highly recommend the IPython interactive interpreter when dealing with questions like this  It lets you type variable name  and will return a whole list of information about the object including the type and the doc string for the type   e g   In  9   var   123  In  10   var  Type        int Base Class   lt type  int  gt  String Form     123 Namespace   Interactive Docstring      int x   base   - gt  integer   Convert a string or number to an integer  if possible   A floating point argument will be truncated towards zero  this does not include a string representation of a floating point number    When converting a string  use the optional base   It is an error to supply a base when converting a         non-string  If the argument is outside the integer range a long object         will be returned instead

User · Answer

a    cool  type a     result  str   lt class  str  gt  or  do   dir a    to see the list of inbuilt methods you can have on the variable

User · Answer

Python doesn t have such types as you describe  There are two types used to represent integral values  int  which corresponds to platform s int type in C  and long  which is an arbitrary precision integer  i e  it grows as needed and doesn t have an upper limit   ints are silently converted to long if an expression produces result which cannot be stored in int

User · Answer

It really depends on what level you mean  In Python 2 x  there are two integer types  int  constrained to sys maxint  and long  unlimited precision   for historical reasons  In Python code  this shouldn t make a bit of difference because the interpreter automatically converts to long when a number is too large  If you want to know about the actual data types used in the underlying interpreter  that s implementation dependent   CPython s are located in Objects intobject c and Objects longobject c   To find out about the systems types look at cdleary answer for using the struct module

User · Answer

How to determine the variable type in Python   So if you have a variable  for example  one   1  You want to know its type  There are right ways and wrong ways to do just about everything in Python  Here s the right way  Use type  gt  gt  gt  type one   lt type  int  gt   You can use the   name   attribute to get the name of the object   This is one of the few special attributes that you need to use the   dunder   name to get to - there s not even a method for it in the inspect module    gt  gt  gt  type one    name    int   Don t use   class   In Python  names that start with underscores are semantically not a part of the public API  and it s a best practice for users to avoid using them   Except when absolutely necessary   Since type gives us the class of the object  we should avoid getting this directly     gt  gt  gt  one   class    This is usually the first idea people have when accessing the type of an object in a method - they re already looking for attributes  so type seems weird  For example  class Foo object       def foo self           self   class    Don t  Instead  do type self   class Foo object       def foo self           type self   Implementation details of ints and floats  How do I see the type of a variable whether it is unsigned 32 bit  signed 16 bit  etc    In Python  these specifics are implementation details  So  in general  we don t usually worry about this in Python  However  to sate your curiosity    In Python 2  int is usually a signed integer equal to the implementation s word width  limited by the system   It s usually implemented as a long in C  When integers get bigger than this  we usually convert them to Python longs  with unlimited precision  not to be confused with C longs   For example  in a 32 bit Python 2  we can deduce that int is a signed 32 bit integer   gt  gt  gt  import sys   gt  gt  gt  format sys maxint   032b    01111111111111111111111111111111   gt  gt  gt  format -sys maxint - 1   032b     minimum value  see docs   -10000000000000000000000000000000   In Python 3  the old int goes away  and we just use  Python s  long as int  which has unlimited precision  We can also get some information about Python s floats  which are usually implemented as a double in C   gt  gt  gt  sys float info sys floatinfo max 1 7976931348623157e 308  max exp 1024  max 10 exp 308   min 2 2250738585072014e-308  min exp -1021  min 10 exp -307  dig 15   mant dig 53  epsilon 2 2204460492503131e-16  radix 2  rounds 1   Conclusion Don t use   class    a semantically nonpublic API  to get the type of a variable  Use type instead  And don t worry too much about the implementation details of Python  I ve not had to deal with issues around this myself  You probably won t either  and if you really do  you should know enough not to be looking to this answer for what to do

User · Answer

a    cool  type a     result  str   lt class  str  gt  or  do   dir a    to see the list of inbuilt methods you can have on the variable

User · Answer

One more way using   class      gt  gt  gt  a    1  2  3  4   gt  gt  gt  a   class    lt type  list  gt   gt  gt  gt  b     key1    val1    gt  gt  gt  b   class    lt type  dict  gt   gt  gt  gt  c   12  gt  gt  gt  c   class    lt type  int  gt

User · Answer

It is so simple  You do it like this   print type variable name

User · Answer

Examples of simple type checking in Python   assert type variable name     int  assert type variable name     bool  assert type variable name     list

User · Answer

Simple  for python 3 4 and above  print  type variable name     Python 2 7 and above  print type variable name

User · Answer

Just do not do it  Asking for something s type is wrong in itself  Instead use polymorphism  Find or if necessary define by yourself the method that does what you want for any possible type of input and just call it without asking about anything  If you need to work with built-in types or types defined by a third-party library  you can always inherit from them and use your own derivatives instead  Or you can wrap them inside your own class  This is the object-oriented way to resolve such problems   If you insist on checking exact type and placing some dirty ifs here and there  you can use   class   property or type function to do it  but soon you will find yourself updating all these ifs with additional cases every two or three commits  Doing it the OO way prevents that and lets you only define a new class for a new type of input instead

User · Answer

How to determine the variable type in Python   So if you have a variable  for example  one   1  You want to know its type  There are right ways and wrong ways to do just about everything in Python  Here s the right way  Use type  gt  gt  gt  type one   lt type  int  gt   You can use the   name   attribute to get the name of the object   This is one of the few special attributes that you need to use the   dunder   name to get to - there s not even a method for it in the inspect module    gt  gt  gt  type one    name    int   Don t use   class   In Python  names that start with underscores are semantically not a part of the public API  and it s a best practice for users to avoid using them   Except when absolutely necessary   Since type gives us the class of the object  we should avoid getting this directly     gt  gt  gt  one   class    This is usually the first idea people have when accessing the type of an object in a method - they re already looking for attributes  so type seems weird  For example  class Foo object       def foo self           self   class    Don t  Instead  do type self   class Foo object       def foo self           type self   Implementation details of ints and floats  How do I see the type of a variable whether it is unsigned 32 bit  signed 16 bit  etc    In Python  these specifics are implementation details  So  in general  we don t usually worry about this in Python  However  to sate your curiosity    In Python 2  int is usually a signed integer equal to the implementation s word width  limited by the system   It s usually implemented as a long in C  When integers get bigger than this  we usually convert them to Python longs  with unlimited precision  not to be confused with C longs   For example  in a 32 bit Python 2  we can deduce that int is a signed 32 bit integer   gt  gt  gt  import sys   gt  gt  gt  format sys maxint   032b    01111111111111111111111111111111   gt  gt  gt  format -sys maxint - 1   032b     minimum value  see docs   -10000000000000000000000000000000   In Python 3  the old int goes away  and we just use  Python s  long as int  which has unlimited precision  We can also get some information about Python s floats  which are usually implemented as a double in C   gt  gt  gt  sys float info sys floatinfo max 1 7976931348623157e 308  max exp 1024  max 10 exp 308   min 2 2250738585072014e-308  min exp -1021  min 10 exp -307  dig 15   mant dig 53  epsilon 2 2204460492503131e-16  radix 2  rounds 1   Conclusion Don t use   class    a semantically nonpublic API  to get the type of a variable  Use type instead  And don t worry too much about the implementation details of Python  I ve not had to deal with issues around this myself  You probably won t either  and if you really do  you should know enough not to be looking to this answer for what to do

User · Answer

Python doesn t have such types as you describe  There are two types used to represent integral values  int  which corresponds to platform s int type in C  and long  which is an arbitrary precision integer  i e  it grows as needed and doesn t have an upper limit   ints are silently converted to long if an expression produces result which cannot be stored in int

User · Answer

Examples of simple type checking in Python   assert type variable name     int  assert type variable name     bool  assert type variable name     list

User · Answer

For python2 x  use   print type variable name    For python3 x  use   print type variable name

User · Answer

Do you mean in Python or using ctypes   In the first case  you simply cannot - because Python does not have signed unsigned  16 32 bit integers   In the second case  you can use type      gt  gt  gt  import ctypes  gt  gt  gt  a   ctypes c uint     unsigned int  gt  gt  gt  type a   lt class  ctypes c ulong  gt    For more reference on ctypes  an its type  see the official documentation

User · Answer

It may be little irrelevant  but you can check types of an object with isinstance object  type  as mentioned here

User · Answer

You may be looking for the type   built-in function   See the examples below  but there s no  unsigned  type in Python just like Java   Positive integer    gt  gt  gt  v   10  gt  gt  gt  type v   lt type  int  gt    Large positive integer    gt  gt  gt  v   100000000000000  gt  gt  gt  type v   lt type  long  gt    Negative integer    gt  gt  gt  v   -10  gt  gt  gt  type v   lt type  int  gt    Literal sequence of characters    gt  gt  gt  v    hi   gt  gt  gt  type v   lt type  str  gt    Floating point integer    gt  gt  gt  v   3 14159  gt  gt  gt  type v   lt type  float  gt

User · Answer

Python doesn t have such types as you describe  There are two types used to represent integral values  int  which corresponds to platform s int type in C  and long  which is an arbitrary precision integer  i e  it grows as needed and doesn t have an upper limit   ints are silently converted to long if an expression produces result which cannot be stored in int

User · Answer

It really depends on what level you mean  In Python 2 x  there are two integer types  int  constrained to sys maxint  and long  unlimited precision   for historical reasons  In Python code  this shouldn t make a bit of difference because the interpreter automatically converts to long when a number is too large  If you want to know about the actual data types used in the underlying interpreter  that s implementation dependent   CPython s are located in Objects intobject c and Objects longobject c   To find out about the systems types look at cdleary answer for using the struct module

User · Answer

Python doesn t have such types as you describe  There are two types used to represent integral values  int  which corresponds to platform s int type in C  and long  which is an arbitrary precision integer  i e  it grows as needed and doesn t have an upper limit   ints are silently converted to long if an expression produces result which cannot be stored in int

User · Answer

Simple  for python 3 4 and above  print  type variable name     Python 2 7 and above  print type variable name

User · Answer

Use the type   builtin function    gt  gt  gt  i   123  gt  gt  gt  type i   lt type  int  gt   gt  gt  gt  type i  is int True  gt  gt  gt  i   123 456  gt  gt  gt  type i   lt type  float  gt   gt  gt  gt  type i  is float True   To check if a variable is of a given type  use isinstance    gt  gt  gt  i   123  gt  gt  gt  isinstance i  int  True  gt  gt  gt  isinstance i   float  str  set  dict   False   Note that Python doesn t have the same types as C C    which appears to be your question

User · Answer

The question is somewhat ambiguous -- I m not sure what you mean by  view   If you are trying to query the type of a native Python object   atzz s answer will steer you in the right direction   However  if you are trying to generate Python objects that have the semantics of primitive C-types   such as uint32 t  int16 t   use the struct module  You can determine the number of bits in a given C-type primitive thusly    gt  gt  gt  struct calcsize  c     char 1  gt  gt  gt  struct calcsize  h     short 2  gt  gt  gt  struct calcsize  i     int 4  gt  gt  gt  struct calcsize  l     long 4   This is also reflected in the array module  which can make arrays of these lower-level types    gt  gt  gt  array array  c   itemsize   char 1   The maximum integer supported  Python 2 s int  is given by sys maxint    gt  gt  gt  import sys  math  gt  gt  gt  math ceil math log sys maxint  2     1   Signedness 32 0   There is also sys getsizeof  which returns the actual size of the Python object in residual memory    gt  gt  gt  a   5  gt  gt  gt  sys getsizeof a    Residual memory  12   For float data and precision data  use sys float info    gt  gt  gt  sys float info sys floatinfo max 1 7976931348623157e 308  max exp 1024  max 10 exp 308  min 2 2250738585072014e-308  min exp -1021  min 10 exp -307  dig 15  mant dig 53  epsilon 2 2204460492503131e-16  radix 2  rounds 1

User · Answer

You may be looking for the type   built-in function   See the examples below  but there s no  unsigned  type in Python just like Java   Positive integer    gt  gt  gt  v   10  gt  gt  gt  type v   lt type  int  gt    Large positive integer    gt  gt  gt  v   100000000000000  gt  gt  gt  type v   lt type  long  gt    Negative integer    gt  gt  gt  v   -10  gt  gt  gt  type v   lt type  int  gt    Literal sequence of characters    gt  gt  gt  v    hi   gt  gt  gt  type v   lt type  str  gt    Floating point integer    gt  gt  gt  v   3 14159  gt  gt  gt  type v   lt type  float  gt

User · Answer

It really depends on what level you mean  In Python 2 x  there are two integer types  int  constrained to sys maxint  and long  unlimited precision   for historical reasons  In Python code  this shouldn t make a bit of difference because the interpreter automatically converts to long when a number is too large  If you want to know about the actual data types used in the underlying interpreter  that s implementation dependent   CPython s are located in Objects intobject c and Objects longobject c   To find out about the systems types look at cdleary answer for using the struct module

[python] How to determine a Python variable's type?

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