Robin Becker wrote:
On 16/09/2017 01:58, Steve D'Aprano wrote:
........
If you want to test for None specifically:
if any(v is None for v in values):
print "at least one value was None"
.......
for some reason that seems slow on my machine when compared with
if None in values:
.....
This does not seem particularly surprising. "None in values" is known
as soon as None is found.
In "any(v is None for v in values)", "any" probably isn't called until
its argument is (fully) known. Of course the results would depend on
the implementation. It would be interesting to compare the results if
you used the optimize option (it's either -o or -O).
Bill
C:\usr\share\robin\pythonDoc>python -m timeit -s"values=(1,2,None)"
"any(v is None for v in values)"
1000000 loops, best of 3: 0.62 usec per loop
C:\usr\share\robin\pythonDoc>python -m timeit
-s"values=(None,2,None)" "any(v is None for v in values)"
1000000 loops, best of 3: 0.504 usec per loop
C:\usr\share\robin\pythonDoc>python -m timeit
-s"values=(None,2,None)" "None in values"
10000000 loops, best of 3: 0.0309 usec per loop
C:\usr\share\robin\pythonDoc>python -m timeit -s"values=(1,2,None)"
"None in values"
10000000 loops, best of 3: 0.097 usec per loop
it also seems a bit less obvious
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