ImageGrid: subset matches on attrs not metas

[ajdapretnar]

Issue

Subset in ImageGrid for some reason matched on metas, so subsets from Confusion Matrix didn't work.

Description of changes

Subset now checks attributes.

Includes

• [X] Code changes
• [ ] Tests
• [ ] Documentation

[codecov[bot]]

Codecov Report

Merging #164 into master will not change coverage. The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #164   +/-   ##
=======================================
  Coverage   61.65%   61.65%           
=======================================
  Files          13       13           
  Lines        3234     3234           
  Branches      481      481           
=======================================
  Hits         1994     1994           
  Misses       1116     1116           
  Partials      124      124

[ajdapretnar]

@PrimozGodec Please check this is ok.

[PrimozGodec]

Closing via #165