Compare to multiple values in an if statement

Question

im going to need multiple if statements comparing to the same couple elements, and was wondering if there was something along these lines i could do to make the code cleaner and easier.

Example would be that this function.

def test(num): 

    a = [1, 2, 3]

    if num == a : 
        return True

    else : 
        return False

would return

>>>test(1)
True
>>>test(2)
True
>>>test(5)
False

Instead of having to write the separate if statements for 1, 2, and 3.

Bhargav Rao · Accepted Answer · 2015-03-31T15:56:12.223

5

Use the in operator

if num in a :

as in

def test(num): 
    a = [1, 2, 3]
    if num in a : 
        return True
    else : 
        return False

a work around would be (as suggested by Padraic)

 def test(num): 
        a = [1, 2, 3]
        return num in a

This would work because, The in operator compares if the LHS is present in the RHS and returns a boolean value respectively.

Also this is possible

test = lambda x:  num in [1, 2, 3]

That is all in a single line!

edited Mar 31 '15 at 15:56

answered Mar 31 '15 at 15:48

Bhargav Rao

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thanks! i cant believe i didnt think of that now – iotaa Mar 31 '15 at 15:52
and how about `return (num in [1, 2, 3])` :) – hexerei software Mar 31 '15 at 15:52
1

@Bhargav, you don't need the parens. – Padraic Cunningham Mar 31 '15 at 15:52
1

@PadraicCunningham But I needed the explanation! :P – Bhargav Rao Mar 31 '15 at 15:55

score 0 · Answer 2 · answered Mar 31 '15 at 16:07

You can use in, or check for the index and catch the error:

num in a will check if the item num is in the list a.

>>> 1 in [1, 2, 5]
True
>>> 3 in [1, 2, 5]
False
>>> 100 in range(101)
True

try getting the index, and except to catch the IndexError:

def isIn(item, lst):
    try:
        lst.index(item)
        return True
    except ValueError:
        return False
    return False

>>> isIn(5, [1, 2, 5])
True
>>> isIn(5, [1, 2, 3])
False

Compare to multiple values in an if statement

2 Answers2

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