[Numpy-discussion] problems with duplicating and slicing an array

Simon Burton simon at arrowtheory.com
Thu Jan 20 17:45:42 CST 2005


On Thu, 20 Jan 2005 20:29:26 -0500
Yun Mao <yunmao at gmail.com> wrote:

> Hi everyone,
>    I have two questions:
> 1. When I do v = u[:, :],  it seems u and v still point to the same
> memory. e.g. When I do v[1,1]=0, u[1,1] will be zero out as well.
> What's the right way to duplicate an array? Now I have to do v =
> dot(u, identity(N)), which is kind of silly.

v = na.array(u)

> 
> 2. Is there a way to do Matlab style slicing? e.g. if I have 
>   i = array([0, 2])
>   x = array([1.1, 2.2, 3.3, 4.4])
>   I wish y = x(i) would give me [1.1, 3.3]
> Now I'm using map, but it gets a little annoying when there are two
> dimensions. Any ideas?

have a look at the "take" method.

Simon.




More information about the Numpy-discussion mailing list