[Numpy-discussion] Matlab -> NumPy translation and indexing
Robert Cimrman
cimrman3 at ntc.zcu.cz
Wed Mar 14 09:46:38 EDT 2007
David Koch wrote:
> Hi,
>
> so one thing I came across now is the following, very simple:
>
> Matlab:
> A = []
> while ....
> A = [A some_scalar_value]
> end
>
>
> In Python, I tried:
>
> A = empty((0,0))
> while ....
> A = concatenate((A, array([someScalarValue])), 1)
> end
>
> which returns an error since the shape of the empty A does not match the
> vector I want to concatenate with. Any way to get around this without
> having
> to use some obscure "if exist A" clause. I am still stuck in my Matlab ways
> - hoping to get rid of them though.
a = empty( (0,) )
...
I would bet that using a regular Python list would be faster in this
case than growing the numpy array.
a = []
while ...
a.append( scalar )
a = array( a )
r.
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