Posted
by user248237
on Stack Overflow
See other posts from Stack Overflow
or by user248237
Published on 2010-05-13T15:32:57Z
Indexed on
2010/05/13
16:14 UTC
Read the original article
Hit count: 409
How can I sort an array in numpy by the nth column? e.g.
a = array([[1,2,3],[4,5,6],[0,0,1]])
I'd like to sort by the second column, such that I get back:
array([[0,0,1],[1,2,3],[4,5,6]])
thanks.
© Stack Overflow or respective owner
as seen on Stack Overflow
- Search for 'Stack Overflow'
I just started programming in python and am very new to numpy packages.. so still trying to get a hang of it.
I have a an numpy_array
so something like [ a b c]
And then I want to append it into anotehr numpyarray
(Just like we create a list of lists)
How do we create an array of numpy arrays containing…
>>> More
as seen on Stack Overflow
- Search for 'Stack Overflow'
I need to sort two arrays simultaneously, or rather I need to sort one of the arrays and bring the corresponding element of its associated array with it as I sort. That is if the array is [(5, 33), (4, 44), (3, 55)] and I sort by the first axis (labeled below dtype='alpha') then I want: [(3.0, 55…
>>> More
as seen on Stack Overflow
- Search for 'Stack Overflow'
I'm trying to batch up a bunch of vertices and texture coords in an interleaved array before sending it to pyOpengl's glInterleavedArrays/glDrawArrays. The only problem is that I'm unable to find a suitably fast enough way to append data into a numpy array.
Is there a better way to do this? I…
>>> More
as seen on Ask Ubuntu
- Search for 'Ask Ubuntu'
I am sorry if this is the wrong section but I am starting to get desperate, please someone help me...
I need to install the program mrcwa-20080820 (sourceforge.net/projects/mrcwa/) because a summer project that I am involved. I need to use it together with anaconda (store.continuum.io/cshop/anaconda/)…
>>> More
as seen on Programmers
- Search for 'Programmers'
The "vectorizing" of fancy indexing by Python's numpy library sometimes gives unexpected results. For example:
import numpy
a = numpy.zeros((1000,4), dtype='uint32')
b = numpy.zeros((1000,4), dtype='uint32')
i = numpy.random.random_integers(0,999,1000)
j = numpy.random.random_integers(0,3,1000)
a[i…
>>> More
as seen on Stack Overflow
- Search for 'Stack Overflow'
Hi: I have installed Scipy (via macports) for Python on my Mac and it runs fine when running Python scripts. But now I'm using Scipy (via PyObjc) for calculations embedded in a Cocoa App frontend. The following error occurs:
ImportError: No module named scipy
I am using the "Python.framework" in…
>>> More
as seen on Stack Overflow
- Search for 'Stack Overflow'
Hi folks,
I can't get scipy to function in 32 bit mode when compiled as a i386/x86_64 universal binary, and executed on my 64 bit 10.6.2 MacPro1,1.
My python setup
With the help of this answer, I built a 32/64 bit intel universal binary of python 2.6.4 with the intention of using the arch command…
>>> More
as seen on Stack Overflow
- Search for 'Stack Overflow'
I'd like to calculate the mathematical rank of a matrix using scipy. The most obvious function numpy.rank calculates the dimension of an array (ie. scalars have dimension 0, vectors 1, matrices 2, etc...). I am aware that the numpy.linalg.lstsq module has this capability, but I was wondering if such…
>>> More
as seen on Stack Overflow
- Search for 'Stack Overflow'
The following code runs too slowly even though everything seems to be vectorized.
from numpy import *
from scipy.sparse import *
n = 100000;
i = xrange(n); j = xrange(n);
data = ones(n);
A=csr_matrix((data,(i,j)));
x = A[i,j]
The problem seems to be that the indexing operation is implemented…
>>> More
as seen on Stack Overflow
- Search for 'Stack Overflow'
I am trying to export a list of text strings from Python to MATLAB using scipy.io. I would like to use scipy.io because my desired .mat file should include both numerical matrices (which I learned to do here) and text cell arrays.
I tried:
import scipy.io
my_list = ['abc', 'def', 'ghi']
scipy.io…
>>> More
