Python: checking type of variables

Question

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!

Since either `isinstance(a, int)` or `isinstance(a, float)` is going to be False, the smartass answer is that the if is always true and can be omitted entirely... — RemcoGerlich, Dec 20 '13 at 13:21
I would just omit the checking and catch any resulting errors in the following code. — Matthias, Dec 20 '13 at 13:28

Alexander Zhukov · Accepted Answer · 2013-12-20T13:24:35.030

5

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.

edited Dec 20 '13 at 13:24

answered Dec 20 '13 at 13:17

Alexander Zhukov

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1

Use generator expression. Otherwise all element are tested. – falsetru Dec 20 '13 at 13:18
1

It should be `not all(...)` or `any(not ...)`. Isn't it? – falsetru Dec 20 '13 at 13:20

score 2 · Answer 2 · answered Dec 20 '13 at 13:19

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
>>>

answered Dec 20 '13 at 13:19

Games Brainiac

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alko · Answer 3 · 2013-12-20T13:23:04.480

1

>>> 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

edited Dec 20 '13 at 13:23

answered Dec 20 '13 at 13:17

alko

46,136
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score 0 · Answer 4 · answered Dec 20 '13 at 13:27

0

Actually, what you've write is equal to

if True:
    do_somthing
    pass

answered Dec 20 '13 at 13:27

Kane Blueriver

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You should have developped your answer – eyquem Dec 20 '13 at 16:58

score -3 · Answer 5 · answered Dec 20 '13 at 16:58

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

Python: checking type of variables

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