How to pass an operator to a python function?

This video explains
How to pass an operator to a python function?

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Music by Eric Matyas
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Track title: Dreamlands

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Chapters
00:00 Question
00:31 Accepted answer (Score 96)
00:47 Answer 2 (Score 56)
01:28 Answer 3 (Score 12)
01:57 Answer 4 (Score 0)
02:14 Thank you

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Full question
https://stackoverflow.com/questions/1859...

Accepted answer links:
[operator module]: http://docs.python.org/2/library/operato...

Answer 2 links:
[operator]: http://docs.python.org/2/library/operato...
[Why is using 'eval' a bad practice?]: https://stackoverflow.com/questions/1832...

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Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...

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Tags
#python #function #python2.7

#avk47

ACCEPTED ANSWER

Score 109

Have a look at the operator module:

import operator
get_truth(1.0, operator.gt, 0.0)

...

def get_truth(inp, relate, cut):    
    return relate(inp, cut)
    # you don't actually need an if statement here

ANSWER 2

Score 59

Make a mapping of strings and operator functions. Also, you don't need if/else condition:

import operator


def get_truth(inp, relate, cut):
    ops = {'>': operator.gt,
           '<': operator.lt,
           '>=': operator.ge,
           '<=': operator.le,
           '==': operator.eq}
    return ops[relate](inp, cut)


print(get_truth(1.0, '>', 0.0)) # prints True
print(get_truth(1.0, '<', 0.0)) # prints False
print(get_truth(1.0, '>=', 0.0)) # prints True
print(get_truth(1.0, '<=', 0.0)) # prints False
print(get_truth(1.0, '==', 0.0)) # prints False

FYI, eval() is evil: Why is using 'eval' a bad practice?

ANSWER 3

Score 14

Use the operator module. It contains all the standard operators that you can use in python. Then use the operator as a functions:

import operator

def get_truth(inp, op, cut):
    return op(inp, cut):

get_truth(1.0, operator.gt, 0.0)

If you really want to use strings as operators, then create a dictionary mapping from string to operator function as @alecxe suggested.

ANSWER 4

Score 1

Use the operator module instead:

import operator
def get_truth(inp, relate, cut):
    rel_ops = {
        '>': operator.gt,
        '<': operator.lt,
        '>=': operator.ge,
        '<=': operator.le,
        '==': operator.eq,
        '!=': operator.ne
    }
    return rel_ops[relate](inp, cut)