Conditional iteration

[Paul Rubin]

at <at at tuko.nl> writes:
> >   for x in (x for x in [-2, -1, 0, 1, 2, 3, 4] if x > 0):
> >        ... more code ...

> Do you know if this generates a new list internally (memory consumption?)

It does not.  That parenthesized expression is a called generator
expression.  It compiles to a small subroutine, more or less, that
gets invoked repeatedly as you iterate through it.

A similar expression with square brackets is called a list
comprehension and does generate a new list.