What does this conditional operator do?

Question

I'm not really sure how to interpret them and i'm still struggling to find out what they're exactly doing..

color = self.color2

color = self.fill1 if color == self.fill2 else self.fill2

what is this exactly saying?

That is not a list comprehension. It is more akin to a ternary conditional operator. — Frédéric Hamidi, Mar 10 '13 at 07:55

David Heffernan · Accepted Answer · 2013-03-10T08:07:50.520

5

This is known as a conditional expression.

The expression x if C else y first evaluates the condition, C (not x); if C is true, x is evaluated and its value is returned; otherwise, y is evaluated and its value is returned.

So, your specific example is equivalent to:

if color == self.fill2:
    color = self.fill1
else:
    color = self.fill2

edited Mar 10 '13 at 08:07

answered Mar 10 '13 at 08:01

David Heffernan

572,264
40
974
1,389

score 3 · Answer 2 · answered Mar 10 '13 at 07:59

3

This is not list comprehension. It is sort of a syntactic sugar. Ironically it is meant to improve readability.

It can be interpreted as:

if color == self.fill2:
    color = self.fill1
else:
    color = self.fill2

answered Mar 10 '13 at 07:59

Anurag Ramdasan

3,807
4
27
49

pradyunsg · Answer 3 · 2013-03-10T08:14:03.457

1

It's a conditional expression See PEP-308.

So something like this

x = true_value if condition else false_value

It can also be written as

if condition:
    x = true_value
else:
    x = false_value

edited Mar 10 '13 at 08:14

answered Mar 10 '13 at 08:07

pradyunsg

13,385
10
36
80

aga · Answer 4 · 2013-03-10T08:08:52.453

0

Well, it says exactly what it says: put the value of self.fill1 into color variable if value of color equals to self.fill1, otherwise put self.fill2. It's called ternary operator, you can find more information about it here.

edited Mar 10 '13 at 08:08

answered Mar 10 '13 at 08:01

aga

25,984
9
77
115

What does this conditional operator do?

4 Answers4