What is the difference between np.array([1, 2]) and np.array([[1, 2]])?
Which one of them is a matrix?
I also do not understand the output for shape of the above tensors. The former returns (2,) and the latter returns (1,2).
>Solution :
np.array([1, 2]) builds an array starting from a list, thus giving you a 1D array with the shape (2, ) since it only contains a single list of two elements.
When using the double [ you are actually passing a list of lists, thus this gets you a multidimensional array, or matrix, with the shape (1, 2).
With the latter you are able to build more complex matrices like:
np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
rendering a 3×3 matrix:
array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])