Sterling - 1 year ago 103

Python Question

I have one large numpy.ndarray array that I want to extract the 4th and 5th columns out of and put those columns into a 2D array. The [i,0] element should be the value on the 4th column and [i,1] should be the element from the 5th column.

I trying to use the numpy.hstack function to do this.

`a = numpy.asarray([1, 2, 3, 4, 5])`

for i in range(5):

a = numpy.vstack([a, numpy.asarray([1, 2, 3, 4, 5])])

combined = np.hstack([a[:,3], a[:,4]])

However, this simply gives me an nx1 array. I have tried multiple approaches using concatenate that look like these examples:

`combined = np.concatenate([a[:,3], a[:,4]])`

combined = np.concatenate([a[:,3], a[:,4]], axis=1)

combined = np.concatenate([a[:,3].T, a[:,4].T])

I feel like hstack is the function I want, but I can't seem to figure out how to make it give me an nx2 array. Can anyone point me in the right direction? Any help is appreciated.