Putting it another way, your example doesn't make sense. How would you
parenthesise it to make it clearer?
[ (x for x in a if x & 1) else 'even'] You have an "else"
without an "if".
[ x for x in (a if x & 1 else 'even')] Using x before it has
been defined, at least in this line of code.
[ (x for x in a) if x & 1 else 'even'] Ditto
Other variants may be possible. Whereas Jelle's correct version can be
written as
[(x if x & 1 else 'even') for x in a] [1, 'even', 3]
Rob Cliffe
On 05/10/2017 16:44, Jelle Zijlstra wrote:
[x if x & 1 else 'even' for x in a]
An `if` at the end of the comprehension means a condition on whether
to include the value.
Also, this question would have been better asked on python-list.
2017-10-05 8:40 GMT-07:00 Jason H <jhihn@gmxcom <mailto:jh...@gmx.com>>:
>>> a = [1,2,3]
>>> [ x for x in a if x & 1]
[1, 3]
>>> [ x for x in a if x & 1 else 'even']
File "<stdin>", line 1
[ x for x in a if x & 1 else 'even']
^
SyntaxError: invalid syntax
I expected [1, 'even', 3]
I would expect that the if expression would be able to provide
alternative values through else.
The work around blows it out to:
l = []
for x in a:
if x&1:
l.append(x)
else:
l.append('even')
Unless there is a better way?
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