Re: pythonic array subsetting

2009-02-17 Thread bearophileHUGS
Nick Matzke: I have to do this hundreds of times, so speed would be useful. Try to create a 2D array with NumPy, and then slice it. Note that slicing syntax has a stride too. Bye, bearophile -- http://mail.python.org/mailman/listinfo/python-list

Re: pythonic array subsetting

2009-02-17 Thread Nick Matzke
Looks like compress is the right numpy function, but it took forever for me to find it... x = array([[1,2,3], [4,5,6], [7,8,9]], dtype=float) compress([1,2], x, axis=1) result: array([[ 1., 2.], [ 4., 5.], [ 7., 8.]]) Gary Herron wrote: Nick Matzke wrote: Hi, So I've

Re: pythonic array subsetting

2009-02-17 Thread Robert Kern
On 2009-02-17 14:36, Nick Matzke wrote: Looks like compress is the right numpy function, but it took forever for me to find it... x = array([[1,2,3], [4,5,6], [7,8,9]], dtype=float) compress([1,2], x, axis=1) result: array([[ 1., 2.], [ 4., 5.], [ 7., 8.]]) No, that's actually not correct.

pythonic array subsetting

2009-02-16 Thread Nick Matzke
Hi, So I've got a square floating point array that is about 1000 x 1000. I need to subset this array as efficiently as possible based on an ordered sublist of the list of rownames/colnames (they are the same, this is a symmetric array). e.g., if sublist is of length 500, and matches the