Fill A Column Of A Numpy Array With Another Array

I have: x = np.zeros((96,11,11,2,10),dtype=np.float64) y = np.array([0,10,20,30,40,50,60,70,80,90,100],dtype=np.float64) x[:,:,:,0,0] = y print x[0,:,:,0,0] i get: [[ 0. 10.

Solution 1:

You need to change y from 1D to 2D (with one column):

x[:,:,:,0,0] = y[:, np.newaxis]

or,

x[:,:,:,0,0] = y.reshape(11,1)

Solution 2:

If you want the output to be the transpose, just do:

>>> import numpy as np
>>> x = np.zeros((96,11,11,2,10),dtype=np.float64)
>>> y = np.array([0,10,20,30,40,50,60,70,80,90,100],dtype=np.float64)
>>> for i in range(x.shape[0]):
>>>    x[i,:,:,0,0] = x[i,:,:,0,0].T
>>> print x[0,:,:,0,0]
 [[   0.    0.    0.    0.    0.    0.    0.    0.    0.    0.    0.]
  [  10.   10.   10.   10.   10.   10.   10.   10.   10.   10.   10.]
  [  20.   20.   20.   20.   20.   20.   20.   20.   20.   20.   20.]
  [  30.   30.   30.   30.   30.   30.   30.   30.   30.   30.   30.]
  [  40.   40.   40.   40.   40.   40.   40.   40.   40.   40.   40.]
  [  50.   50.   50.   50.   50.   50.   50.   50.   50.   50.   50.]
  [  60.   60.   60.   60.   60.   60.   60.   60.   60.   60.   60.]
  [  70.   70.   70.   70.   70.   70.   70.   70.   70.   70.   70.]
  [  80.   80.   80.   80.   80.   80.   80.   80.   80.   80.   80.]
  [  90.   90.   90.   90.   90.   90.   90.   90.   90.   90.   90.]
  [ 100.  100.  100.  100.  100.  100.  100.  100.  100.  100.  100.]]

It updates the first dimension, this is the output for 34th index:

>>> print x[34,:,:,0,0]
 [[   0.    0.    0.    0.    0.    0.    0.    0.    0.    0.    0.]
  [  10.   10.   10.   10.   10.   10.   10.   10.   10.   10.   10.]
  [  20.   20.   20.   20.   20.   20.   20.   20.   20.   20.   20.]
  [  30.   30.   30.   30.   30.   30.   30.   30.   30.   30.   30.]
  [  40.   40.   40.   40.   40.   40.   40.   40.   40.   40.   40.]
  [  50.   50.   50.   50.   50.   50.   50.   50.   50.   50.   50.]
  [  60.   60.   60.   60.   60.   60.   60.   60.   60.   60.   60.]
  [  70.   70.   70.   70.   70.   70.   70.   70.   70.   70.   70.]
  [  80.   80.   80.   80.   80.   80.   80.   80.   80.   80.   80.]
  [  90.   90.   90.   90.   90.   90.   90.   90.   90.   90.   90.]
  [ 100.  100.  100.  100.  100.  100.  100.  100.  100.  100.  100.]]

Solution 3:

The problem is simple: you're using a row vector for y instead of a column vector, so it's filling by row instead of by column.

More technically, you've got an array of shape (11,), instead of an array of (11, 1), so it broadcasts to (1, 11) when filling a 2D array.

Compare:

>>> x = np.zeros((96,11,11,2,10),dtype=np.float64)
>>> y = np.array([[0],[10],[20],[30],[40],[50],[60],[70],[80],[90],[100]],dtype=np.float64)
>>> x[:,:,:,0,0]=y
>>> print x[0,:,:,0,0]
[[   0.    0.    0.    0.    0.    0.    0.    0.    0.    0.    0.]
 [  10.   10.   10.   10.   10.   10.   10.   10.   10.   10.   10.]
 [  20.   20.   20.   20.   20.   20.   20.   20.   20.   20.   20.]
 [  30.   30.   30.   30.   30.   30.   30.   30.   30.   30.   30.]
 [  40.   40.   40.   40.   40.   40.   40.   40.   40.   40.   40.]
 [  50.   50.   50.   50.   50.   50.   50.   50.   50.   50.   50.]
 [  60.   60.   60.   60.   60.   60.   60.   60.   60.   60.   60.]
 [  70.   70.   70.   70.   70.   70.   70.   70.   70.   70.   70.]
 [  80.   80.   80.   80.   80.   80.   80.   80.   80.   80.   80.]
 [  90.   90.   90.   90.   90.   90.   90.   90.   90.   90.   90.]
 [ 100.  100.  100.  100.  100.  100.  100.  100.  100.  100.  100.]]

Of course in your real code, y probably isn't a literal, but a result of some earlier computation. (And even if it is a literal, you don't want to type all those extra brackets.) So, assume y is inherently a row vector, as we have to deal with it.

So, just reshape it on the fly:

>>> x = np.zeros((96,11,11,2,10),dtype=np.float64)
>>> y = np.array([0,10,20,30,40,50,60,70,80,90,100],dtype=np.float64)
>>> x[:,:,:,0,0] = y.reshape((11, 1))

Same result.