array subset could be improved? -repost ;)

[Jim O'D]

Hi all

I have an array a=array([2,3,-1]).

I want to extract an array with all the elements of a that are less than 0.

Method 1.
new = array([i for i in a if i < 0])

Method 2.
new = a[nonzero(a<0)]

I'm using Numeric arrays but can't seem to find a function that does this.

Am I missing a more obvious way to do it quickly?

Thanks

Jim

[jon]

Jim O'D wrote:

Hi all

I have an array a=array([2,3,-1]).

I want to extract an array with all the elements of a that are less than 0.

Method 1.
new = array([i for i in a if i < 0])

Method 2.
new = a[nonzero(a<0)]

I'm using Numeric arrays but can't seem to find a function that does this.

Am I missing a more obvious way to do it quickly?

Thanks

Jim

[jon]

Jim O'D wrote:

Hi all

I have an array a=array([2,3,-1]).

I want to extract an array with all the elements of a that are less than 0.

Method 1.
new = array([i for i in a if i < 0])

Method 2.
new = a[nonzero(a<0)]

I'm using Numeric arrays but can't seem to find a function that does this.

Am I missing a more obvious way to do it quickly?

Thanks

Jim

a2=Numeric.compress(a<0,a)

[Fernando Perez]

Jim O'D wrote:

Hi all

I have an array a=array([2,3,-1]).

I want to extract an array with all the elements of a that are less than 0.

Numeric is currently changing into the new scipy core. If you are willing to
play with beta code, get it here:

http://numeric.scipy.org

if not, wait a little for an official release.

With the new numeric, you'll be able to do:

negatives = a[a<0]

Cheers,

f

[Jim O'D]

With the new numeric, you'll be able to do:

negatives = a[a<0]

Cheers,

f

Ooh, that's nice.

Jim