for loop in a single statement with list append function

Question

When i execute the below code, i get the right results:

for i in quorum:
    lst.append(i.strip('l'))
 print lst

 op:
    ['val1', 'val2', 'val3']

but when i try to have the for loop along with list append function in single line, i don't get the expected output (i.e the list elements as above).

what am i missing ? and why does it behave that way ?

lst.append(i.strip('l') for i in quorum)
print lst

op:
[<generator object <genexpr> at 0x2996cd0>]

if argument is iterable and you want to add all elements from said iterable, you are looking for list.extend method. list.append adds argument to list, in your case iterable (generator expression) itself. — Łukasz Rogalski
– Łukasz Rogalski, Commented May 5, 2016 at 12:08

Ignacio Vazquez-Abrams · Accepted Answer · 2016-05-05 12:07:37Z

5

The expression in parens is a generator expression (genex). It is an iterable, but list.append() doesn't iterate. Fortunately list.extend() does:

lst.extend(i.strip('l') for i in quorum)

answered May 5, 2016 at 12:07

Ignacio Vazquez-Abrams

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