[Numpy-discussion] fastest way to make two vectors into an array
Pearu Peterson
pearu at cens.ioc.ee
Thu Jan 30 01:51:09 CST 2003
On Wed, 29 Jan 2003, John Hunter wrote:
>
> I have two equal length 1D arrays of 256-4096 complex or floating
> point numbers which I need to put into a shape=(len(x),2) array.
>
> I need to do this a lot, so I would like to use the most efficient
> means. Currently I am doing:
>
> def somefunc(x,y):
> X = zeros( (len(x),2), typecode=x.typecode())
> X[:,0] = x
> X[:,1] = y
> do_something_with(X)
>
> Is this the fastest way?
May be you could arange your algorithm so that you first create
X and then reference its columns by x,y without copying:
# Allocate memory
X = zeros( (n,2), typecode=.. )
# Get references to columns
x = X[:,0]
y = X[:,1]
while 1:
do_something_inplace_with(x,y)
do_something_with(X)
Pearu
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