As the NumPy documentation says, numpy.ndim(a) returns:

The number of dimensions in a. Scalars are zero-dimensional

E.g.:

a = np.array(111)
b = np.array([1,2])
c = np.array([[1,2], [4,5]])
d = np.array([[1,2,3,], [4,5]])
print a.ndim, b.ndim, c.ndim, d.ndim
#outputs: 0 1 2 1

Note that the last array, d, is an array of object dtype, so its dimension is still 1.

What you want to use could be a.shape (or a.size for a one-dimensional array):

print a.size, b.size
print c.size # == 4, which is the total number of elements in the array
# Outputs:
1 2
4

Method .shape returns you a tuple, and you should get your dimension using [0]:

print a.shape, b.shape, b.shape[0]
() (2L,) 2