what does np.hstack do code example

Example: np.hstack

# np.hstack concatenates arrays column-wise

a = np.array([1], [2], [3]) #read as a vector, i.e. a column
b = np.array([4], [5], [6]) #read as a vector, i.e. a column 
							#concatenated to the first one
c = np.hstack((a, b)))
print(c)
# output is
# [[1, 4],
#  [2, 5],
#  [3, 6]]