On 3/23/07, Eric Firing <[EMAIL PROTECTED]> wrote: > Sebastian Haase wrote: > > On 3/22/07, Stefan van der Walt <[EMAIL PROTECTED]> wrote: > >> On Thu, Mar 22, 2007 at 08:13:22PM -0400, Brian Blais wrote: > >>> Hello, > >>> > >>> I'd like to concatenate a couple of 1D arrays to make it a 2D array, with > >>> two columns > >>> (one for each of the original 1D arrays). I thought this would work: > >>> > >>> > >>> In [47]:a=arange(0,10,1) > >>> > >>> In [48]:a > >>> Out[48]:array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]) > >>> > >>> In [49]:b=arange(-10,0,1) > >>> > >>> In [51]:b > >>> Out[51]:array([-10, -9, -8, -7, -6, -5, -4, -3, -2, -1]) > >>> > >>> In [54]:concatenate((a,b)) > >>> Out[54]: > >>> array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -10, -9, -8, > >>> -7, -6, -5, -4, -3, -2, -1]) > >>> > >>> In [55]:concatenate((a,b),axis=1) > >>> Out[55]: > >>> array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -10, -9, -8, > >>> -7, -6, -5, -4, -3, -2, -1]) > >>> > >>> > >>> but it never expands the dimensions. Do I have to do this... > >>> > >>> In [65]:concatenate((a.reshape(10,1),b.reshape(10,1)),axis=1) > >>> Out[65]: > >>> array([[ 0, -10], > >>> [ 1, -9], > >>> [ 2, -8], > >>> [ 3, -7], > >>> [ 4, -6], > >>> [ 5, -5], > >>> [ 6, -4], > >>> [ 7, -3], > >>> [ 8, -2], > >>> [ 9, -1]]) > >>> > >>> > >>> ? > >>> > >>> I thought there would be an easier way. Did I overlook something? > >> How about > >> > >> N.vstack((a,b)).T > >> > > Also mentioned here should be the use of > > newaxis. > > As in > > a[:,newaxis] > > > > However I never got a "good feel" for how to use it, so I can't > > complete the code you would need. > > n [9]:c = N.concatenate((a[:,N.newaxis], b[:,N.newaxis]), axis=1) > > In [10]:c > Out[10]: > array([[ 0, -10], > [ 1, -9], > [ 2, -8], > [ 3, -7], > [ 4, -6], > [ 5, -5], > [ 6, -4], > [ 7, -3], > [ 8, -2], > [ 9, -1]]) >
Then of course, there's r_ and c_: c = numpy.c_[a,b] c = numpy.r_[a[None],b[None]].T --bb _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
