Numpy Cheatsheet
Also check the numpy quickstart tutorial!
Array
| Action | Command | Result |
|---|---|---|
| Create Array | a=np.array([1,2,3]) |
[1,2,3] |
| Create multi-dim Array | b=np.array([[0.9, 0.8, 7.0],[0.3, 0.11, 7.0]]) |
[[0.9 0.8 7. ] [0.3 0.11 7. ]] |
| Shape | a.shape b.shape |
(3,) (2, 3) |
| Mem Type | a.dtypeb.dtype |
int32 float64 |
| Item Size | a.itemsizeb.itemsize |
4 8 |
| Single Element | b[1,3] |
7.0 |
| Single Row | b[0,:] |
[0.9 0.8 7. ] |
| Single Collumn | b[:,2] |
[7. 7.] |
| Sub-Array | b[0, 1:-1:2] elements row 0 from 1 to -1 by step 2 |
[0.8] |
| Assign Element | a[1]=20 |
[1 20 3] |
Initializing Different Types of Arrays
| Action | Command | Result |
|---|---|---|
| All zero array | np.zeros(5)np.zeros((2,3)) |
[0. 0. 0. 0. 0.] [[0. 0. 0.] [0. 0. 0.]] |
| All-ones array | np.ones(5) |
[1. 1. 1. 1. 1.] |