How to condense if/else into one line in Python?

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Possible Duplicate:
Python Ternary Operator
Putting a simple if-then statement on one line

Is there a way to compress an if/else statement to one line in Python?
I oftentimes see all sorts of shortcuts and suspect it can apply here too.

http://stackoverflow.com/questions/1686390/python-equivalent-of-short-form-if-in-c http://docs.python.org/reference/compound_stmts.html — TheZ, Jul 17 '12 at 19:15
That's the question you wanted to link: http://stackoverflow.com/questions/394809/python-ternary-operator — kay, Jul 17 '12 at 19:17
another reference: http://stackoverflow.com/questions/7778400/is-there-control-flow-in-python — clwen, Jul 17 '12 at 19:17
@ProjectAnova I down voted your question b/c you did not spent a single second to google your question. — kay, Jul 17 '12 at 19:18
My account has been locked from making any additional questions... what a joke! — AnovaVariance, Jul 17 '12 at 19:24
***This*** is the question I was thinking of: http://stackoverflow.com/questions/11491944/better-way-than-using-if-else-statement-in-python — Levon, Jul 17 '12 at 19:26
@ProjectAnova You might want to try to read the [faq] and use the search function when the lock gets lifted. — millimoose, Jul 17 '12 at 19:32
Conditional expressions don't cover all cases (or all versions). Now what? — Brent Bradburn, Feb 05 '13 at 19:57

score 277 · Answer 1 · edited May 23 '17 at 12:18

277

An example of Python's way of doing "ternary" expressions:

i = 5 if a > 7 else 0

translates into

if a > 7:
   i = 5
else:
   i = 0

This actually comes in handy when using list comprehensions, or sometimes in return statements, otherwise I'm not sure it helps that much in creating readable code.

The readability issue was discussed at length in this recent SO question better way than using if-else statement in python.

It also contains various other clever (and somewhat obfuscated) ways to accomplish the same task. It's worth a read just based on those posts.

edited May 23 '17 at 12:18

Community

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answered Jul 17 '12 at 19:15

Levon

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How do i use it in the return statement? `return count if (count * (distance < within_radius)) > 0 else (continue)` – technazi Oct 31 '18 at 23:38

score 64 · Answer 2 · answered Jul 17 '12 at 19:15

64

Python's if can be used as a ternary operator:

>>> 'true' if True else 'false'
'true'
>>> 'true' if False else 'false'
'false'

answered Jul 17 '12 at 19:15

sloth

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Just want to add the "true" command-line one-line syntax for the that. I have searched a lot how to do that, but no one answer contains this information: $ python -c "import sys; var=1; [ sys.stdout.write('POS\n') if var>0 else sys.stdout.write('NEG\n')]" – Alexander Samoylov Oct 08 '18 at 10:38

score 34 · Answer 3 · answered Jul 17 '12 at 19:14

34

Only for using as a value:

x = 3 if a==2 else 0

or

return 3 if a==2 else 0

answered Jul 17 '12 at 19:14

f p

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This is not restricted to assignment. It can be used in any expression. – BrenBarn Jul 17 '12 at 19:16
Great. This could be the easiest and crazy syntax. – Gaurav Koradiya Jan 20 '20 at 11:36

score 25 · Answer 4 · answered Jul 17 '12 at 19:16

There is the conditional expression:

a if cond else b

but this is an expression, not a statement.

In if statements, the if (or elif or else) can be written on the same line as the body of the block if the block is just one like:

if something: somefunc()
else: otherfunc()

but this is discouraged as a matter of formatting-style.

How to condense if/else into one line in Python?

4 Answers4

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