consistency: extending arrays vs. multiplication ?

Soeren Sonnenburg python-ml at
Sat Jul 23 18:30:02 CEST 2005

Hi all,

Just having started with python, I feel that simple array operations '*'
and '+' don't do multiplication/addition but instead extend/join an

>>> b=[4,5,6]
>>> a+b
[1, 2, 3, 4, 5, 6]

instead of what I would have expected:


>>> 2*a
[1, 2, 3, 1, 2, 3]

Well it is consistent to strings but tolerating string-operations to be
special is ok to me as "a" + "b" -> 'ab' :)
Why not make it another function like a.stretch() or a.expand() and
a.extend() is there doing the same anyway and is more readable...

Putting this in a larger view: 
Ufuncs are very reasonable sin(a), etc ... all that won't work because
of that '+','*' syntax. Ok I can use numarray for that, but seeing its
PEP and a possible inclusion into python at some point that
inconsistency is giving me quite some headache...

Will that change in the future ? Or is this 100*[0] syntax put into
stone for all ages ?


PS: As I am very new to python please forgive/correct me!

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