What does it mean to have an index to scalar variable error? python

exponent is a 1D array. This means that exponent[0] is a scalar, and exponent[0][i] is trying to access it as if it were an array.

Did you mean to say:

L = identity(len(l))
for i in xrange(len(l)):
    L[i][i] = exponent[i]

or even

L = diag(exponent)

?

In my case, I was getting this error because I had an input named x and I was creating (without realizing it) a local variable called x. I thought I was trying to access an element of the input x (which was an array), while I was actually trying to access an element of the local variable x (which was a scalar).

IndexError: invalid index to scalar variable happens when you try to index a numpy scalar such as numpy.int64 or numpy.float64. It is very similar to TypeError: 'int' object has no attribute '__getitem__' when you try to index an int.

>>> a = np.int64(5)
>>> type(a)
<type 'numpy.int64'>
>>> a[3]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
IndexError: invalid index to scalar variable.
>>> a = 5
>>> type(a)
<type 'int'>
>>> a[3]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object has no attribute '__getitem__'