How to construct matrix from vectors?

[Dave Farrance]

Fabien <fabien.maussion at gmail.com> wrote:

>another solution with less "(([[]]))", and less ";". There are way too 
>many ";" in Matlab ;)
>
>import numpy as np
>v1 = [1, 2, 3]
>v2 = [4, 5, 6]
>v3 = [7, 8, 9]
>v4 = [10, 11, 12]
>np.hstack([[v1, v2], [v3, v4]]).T
>Out[]:
>array([[ 1,  4],
>        [ 2,  5],
>        [ 3,  6],
>        [ 7, 10],
>        [ 8, 11],
>        [ 9, 12]])

Neat. And if the OP wants "vectors" in np array form to start with, and
to stack them together without transposing at that point, he could do it
like this:

>>> v1=np.vstack([1,2,3])
>>> v2=np.vstack([4,5,6])
>>> v3=np.vstack([7,8,9])
>>> v4=np.vstack([10,11,12])
>>> np.r_[np.c_[v1,v2],np.c_[v3,v4]]
array([[ 1,  4],
       [ 2,  5],
       [ 3,  6],
       [ 7, 10],
       [ 8, 11],
       [ 9, 12]])

And since he seems to want a Matlab-like environment, then the somewhat
depreciated pylab was intended to dump a Matlab-like set of functions
into the namespace, which is OK for an interactive environment, an not
too much of a problem for a short program in a single module. Probably
best to do that with iPython, though.

>>> from matplotlib.pylab import *
>>> v1=vstack([1,2,3])
>>> v2=vstack([4,5,6])
>>> v3=vstack([7,8,9])
>>> v4=vstack([10,11,12])
>>> r_[c_[v1,v2],c_[v3,v4]]
array([[ 1,  4],
       [ 2,  5],
       [ 3,  6],
       [ 7, 10],
       [ 8, 11],
       [ 9, 12]])