Sklearn depreating linear sum

[ghar1821]

Looks like linear_assignment is being moved from sklearn to scipy. The warning says the move is permanent from 0.23 onwards.

DeprecationWarning: The linear_assignment function is deprecated in 0.21 and will be removed from 0.23. Use scipy.optimize.linear_sum_assignment instead..

Consider changing the imports.

[HichemAK]

There is also an issue with the function coclust.evaluation.external.accuracy which uses scipy.optimize.linear_sum_assignment to find the best correspondence between true labels and predicted labels.

In the file coclust/evaluation/external.py, I propose to replace line 36 which is:

for row, column in indexes:

by:

for row, column in np.stack(indexes, axis=1)

Because indexes, which is the output of the function scipy.optimize.linear_sum_assignment, does not have the right format for the loop.

A simple example to test the function : accuracy(np.array([1,2,3,1,2]), np.array([2,1,3,2,1]))