python

Ubuntu Docker + python3

abgoswam python

I recently had to do a quick test of using python with ubuntu. I decided to use docker.

steps:

sudo docker run -it ubuntu bash

apt-get update
apt-get install python3-pip

# python3 --version
Python 3.8.5

to load up other stuff

sudo docker run -it -v $HOME:/work pytorch/pytorch:1.6.0-cuda10.1-cudnn7-devel bash

sudo docker run -it --ipc=host --rm -v $HOME:/work --privileged pytorch/pytorch:1.6.0-cuda10.1-cudnn7-devel bash

Beyond Integer indexing

abgoswam numpy, python

Faced an interesting problem recently

a : (B, S, T)
b : (B, C)  where 0 <= x[i, j] < S

What I want is an array of shape (B, C, T)

a = np.array(
   ...:    [[[0,1,2,3], 
   ...:      [4,5,6,7],
   ...:      [8,9,10,11]],
   ...:     [[0,1,2,3],
   ...:      [4,5,6,7],
   ...:      [8,9,10,11]]])

b = np.array(
   ...:    [[0,2,2],
   ...:     [1,0, 2]])

a.shape
Out[79]: (2, 3, 4)

b.shape
Out[80]: (2, 3)

What I expect is this

array([[[ 0,  1,  2,  3],
        [ 8,  9, 10, 11],
        [ 8,  9, 10, 11]],
       [[ 4,  5,  6,  7],
        [ 0,  1,  2,  3],
        [ 8,  9, 10, 11]]])

Note this is different from the typical scenario

Initially I hit some issues with integer index broadcasting. It seems it is possible to do it.

a[np.array([np.arange(2)]).T, b]

References:

Numpy RuntimeWarning

abgoswam python

Something I learns recently..

  • NumPy has its own internal warning architecture on top of Pythons, which can be specifically controlled
  • So, something Numpy will just produce a RuntimeWarning  without actually throwing an exception

Consider this:

probs = np.array([0.0, 1.0])
np.prod(probs)**(-1/len(probs))

Numpy produces a RuntimeWarning, not an exception

References: