I have an expression that yields the following result:
array([[0.5],
[0. ]])
I want to make a diagonal 2X2 matrix which has 0.5 and 0 on its diagonal. But when I use the following code:
np.diag(A)
A being the above array, I get the following result:
array([0.5])
Why does python not include the second element from A on the array and how can I include it?
CodePudding user response:
x
is 2d:
In [106]: x=np.array([[0.5],
...: [0. ]])
In [107]: x
Out[107]:
array([[0.5],
[0. ]])
In [108]: x.shape
Out[108]: (2, 1)
Read diag
docs - given a 2d array, it returns the diagonal:
In [109]: np.diag(x)
Out[109]: array([0.5])
Given a 1d array it returns a 2d array:
In [110]: np.diag(x[:,0])
Out[110]:
array([[0.5, 0. ],
[0. , 0. ]])