davrot/pytutorial
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Update README.md

Browse source 
Signed-off-by: David Rotermund <54365609+davrot@users.noreply.github.com>
This commit is contained in:
David Rotermund 2023-12-13 16:42:45 +01:00 committed by GitHub
parent b298ae53fd
commit a7ad2bef63
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
1 changed files with 32 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

32
numpy/new_matrix/README.md
View file

@ -117,6 +117,38 @@ M = np.zeros((2, *d))
print(M) print(M)
``` ```
## np.empty is not np.zeros
If you are sure that you don’t care about what is inside the matrix in the beginning use​
```python
M = numpy.empty((DIM_0, DIM_1, DIM_2,...))​
```
Empty claims a region in the memory and uses it for a matrix. Zeros goes one step further. It fills the memory with zeros.
Thus random junk​ (i.e. data that was stored prior at that memory position) with be the content of a matrix if you use empty. However, np.empty() is faster than np.zeros().
```python
​import numpy as np
M = np.empty((10, 4))
print(M)
```
```python
[[1.66706425e-316 0.00000000e+000 6.89933729e-310 6.89933730e-310]
[6.89933729e-310 6.89933730e-310 6.89933729e-310 6.89933730e-310]
[6.89933730e-310 6.89933730e-310 6.89933729e-310 6.89933729e-310]
[6.89933730e-310 6.89933729e-310 6.89933730e-310 6.89933729e-310]
[6.89933730e-310 4.30513389e-317 4.30321296e-317 6.89933825e-310]
[4.30389280e-317 6.89933822e-310 4.30366750e-317 6.89933822e-310]
[4.30311810e-317 4.30480583e-317 4.30462401e-317 4.30336316e-317]
[6.89933822e-310 4.30386513e-317 4.30358055e-317 4.30571886e-317]
[4.30568724e-317 4.30659237e-317 6.89933822e-310 6.89933822e-310]
[6.89933822e-310 6.89933822e-310 4.30289676e-317 6.89920336e-310]]
```
## [From shape or value](https://numpy.org/doc/stable/reference/routines.array-creation.html#from-shape-or-value) ## [From shape or value](https://numpy.org/doc/stable/reference/routines.array-creation.html#from-shape-or-value)
||| |||