Ben Bush wrote:
On Dec 26, 4:46 pm, Tim Chase <python.l...@tim.thechases.com> wrote:
What does *not* work is
3 * [0,1,2]
As you know, this gives
[0,1,2,0,1,2,0,1,2]
What I am hoping for is
[0,3,6]
I see that I can use
numpy.multiply(3,range(3))
but this seems overkill to me. Can you tell I am coming to Python from
Matlab?
The common way to do this is just
a1 = [0,1,2]
a2 = [x * 3 for x in a1]
or, if you need a1 to be done in place:
a1[:] = [x*3 for x in a1]
There is some subtlety here. The latter says to empty the list assigned
to the name "a1" and refill it with the products. Other references to
the same list will now reflect this operation. This procedure is not
equivalent to reassigning the name "a1". For example:
py> a = [1, 2, 3]
py> a1 = a
py> a1[:] = [x*3 for x in a1]
py> a1
[3, 6, 9]
py> a1
[3, 6, 9]
Whereas:
py> a = [1, 2, 3]
py> a1 = a
py> a1
[1, 2, 3]
py> a1 = [x*3 for x in a1]
py> a1
[3, 6, 9]
py> a
[1, 2, 3]
James
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095
http://www.jamesstroud.com
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