In Python, is it better to use list comprehensions or for-each loops?

Question

Which of the following is better to use and why?

Method 1:

for k, v in os.environ.items():
       print \"%s=%s\" % (k, v)

Method 2

Answer 1

If the iteration is being done for its side effect ( as it is in your "print" example ), then a loop is clearer.

If the iteration is executed in order to build a composite value, then list comprehensions are usually more readable.