python - How can I use if/else in a dictionary comprehension?

Question

Does there exist a way in Python 2.7+ to make something like the following?

{ something_if_true if condition else something_if_false for key, value in dict_.items() }

I know you can make anything with just 'if':

{ something_if_true for key, value in dict_.items() if condition}

Answer 1

You've already got it: A if test else B is a valid Python expression. The only problem with your dict comprehension as shown is that the place for an expression in a dict comprehension must have two expressions, separated by a colon:

{ (some_key if condition else default_key):(something_if_true if condition
          else something_if_false) for key, value in dict_.items() }

The final if clause acts as a filter, which is different from having the conditional expression.