Putting an if-elif-else statement on one line?

Matt Elson picture Matt Elson · Dec 25, 2012 · Viewed 183.9k times · Source

I have read the links below, but it doesn't address my question.
Does Python have a ternary conditional operator? (the question is about condensing if-else statement to one line)

Is there an easier way of writing an if-elif-else statement so it fits on one line?
For example,

if expression1:
   statement1
elif expression2:
   statement2
else:
   statement3

Or a real-world example:

if i > 100:
    x = 2
elif i < 100:
    x = 1
else:
    x = 0

I just feel if the example above could be written the following way, it could look like more concise.

x=2 if i>100 elif i<100 1 else 0 [WRONG]

Answer

Tim Pietzcker picture Tim Pietzcker · Dec 25, 2012

No, it's not possible (at least not with arbitrary statements), nor is it desirable. Fitting everything on one line would most likely violate PEP-8 where it is mandated that lines should not exceed 80 characters in length.

It's also against the Zen of Python: "Readability counts". (Type import this at the Python prompt to read the whole thing).

You can use a ternary expression in Python, but only for expressions, not for statements:

>>> a = "Hello" if foo() else "Goodbye"

Edit:

Your revised question now shows that the three statements are identical except for the value being assigned. In that case, a chained ternary operator does work, but I still think that it's less readable:

>>> i=100
>>> a = 1 if i<100 else 2 if i>100 else 0
>>> a
0
>>> i=101
>>> a = 1 if i<100 else 2 if i>100 else 0
>>> a
2
>>> i=99
>>> a = 1 if i<100 else 2 if i>100 else 0
>>> a
1