Python-List Parse/builder expression

List parsing type:

[Expr for Iter_var in iterable if COND_EXPR]

Generator expression:

(Expr for Iter_var in iterable if cond_expr)

　　

The difference between the two:

-the list parsing needs to generate all the data;

-The generator parse does not actually create the list, but instead returns a generator that yields the entry after each calculation of an entry. The generator expression uses deferred computation, which is more efficient in using memory.

Python-List Parse/builder expression