Python: checking type of variables

问题

I have a question about python.

I have variables a, b, c and d.

And I have the following line:

if    not isinstance(a, int)   or not isinstance(b, int)  \
   or not isinstance(c, int)   or not isinstance(d, int)  \
   or not isinstance(a, float) or not isinstance(b, float)\
   or not isinstance(c, float) or not isinstance(d, float):
    do something

Is it possible to make this code shorter?

Thanks!

回答1:

U should use all:

if not all(isinstance(var, (int, float)) for var in [a, b, c, d]):
    # do stuff

Note, that you can supply both int and 'float' to the isinstance call.

回答2:

Try the following:

>>> a = 1
>>> b = 1.0
>>> c = 123
>>> d = 233
>>> any((type(var) in (int, float) for var in [a,b,c,d]))
True
>>> c = 'hello'
>>> any((type(var) in (int, float) for var in [a,b,c,d]))
True
>>>

回答3:

>>> a = b = c = d = []
>>> any(not isinstance(x, (int, float)) for x in [a,b,c,d])
True
>>> d = 0
>>> any(not isinstance(x, (int, float)) for x in [a,b,c,d])
False

回答4:

Actually, what you've write is equal to

if True:
    do_somthing
    pass

回答5:

Clearly, you didn't take enough attention to the RemcoGerlich's comment, since you upvoted and accepted a senseless answer.
At the time I write this, 4 other people upvoted the same senseless answer.
That's incredible.
Will you see better with this ? :

def OP(a,b,c):
    return    not isinstance(a, int)\
           or not isinstance(b, int)\
           or not isinstance(c, int)\
           or not isinstance(a, float)\
           or not isinstance(b, float)\
           or not isinstance(c, float)

def AZ(a,b,c):
    return all(isinstance(var, (int, float))
               for var in [a, b, c])

gen = ((a,b,c) for a in (1, 1.1 ,'a')
       for b in (2, 2.2, 'b') for c in (3, 3.3, 'c'))

print '                  OPv | AZv     OPv is AZv\n'\
      '                 -----|-----    -----------'
OPV_list = []
for a,b,c in gen:
    OPv = OP(a,b,c)
    OPV_list.append(OPv)
    AZv = AZ(a,b,c)
    print '%3r  %3r  %3r    %s | %s      %s'\
          % (a,b,c,OPv,AZv,OPv is AZv if OPv is not AZv else '')

print '-------------    ----'
print 'all(OPV_list) : ',all(OPV_list)

result
OPv = yours
AZv = senseless answer
I limited to a,b,c to make it short

                  OPv | AZv     OPv is AZv
                 -----|-----    -----------
  1    2    3    True | True      
  1    2  3.3    True | True      
  1    2  'c'    True | False      False
  1  2.2    3    True | True      
  1  2.2  3.3    True | True      
  1  2.2  'c'    True | False      False
  1  'b'    3    True | False      False
  1  'b'  3.3    True | False      False
  1  'b'  'c'    True | False      False
1.1    2    3    True | True      
1.1    2  3.3    True | True      
1.1    2  'c'    True | False      False
1.1  2.2    3    True | True      
1.1  2.2  3.3    True | True      
1.1  2.2  'c'    True | False      False
1.1  'b'    3    True | False      False
1.1  'b'  3.3    True | False      False
1.1  'b'  'c'    True | False      False
'a'    2    3    True | False      False
'a'    2  3.3    True | False      False
'a'    2  'c'    True | False      False
'a'  2.2    3    True | False      False
'a'  2.2  3.3    True | False      False
'a'  2.2  'c'    True | False      False
'a'  'b'    3    True | False      False
'a'  'b'  3.3    True | False      False
'a'  'b'  'c'    True | False      False
-------------    ----
all(OPV_list) :  True

来源：https://stackoverflow.com/questions/20704455/python-checking-type-of-variables

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python

isinstance