[FIX] Scatter Plot Graph: crash on metas column with all 0 values

[jerneju]

Issue

Scaling does not stack metas with other arrays when metas array has all values set to zero.

Description of changes

Another check for metas array.

Includes

• Code changes
• Tests
• Documentation

[codecov-io]

Codecov Report

Merging #2775 into master will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2775      +/-   ##
==========================================
- Coverage   76.08%   76.07%   -0.02%     
==========================================
  Files         338      338              
  Lines       59717    59720       +3     
==========================================
- Hits        45438    45433       -5     
- Misses      14279    14287       +8

[markotoplak]

I do not understand why was this needed. As far as I know, numpy hstack works with zeros as well.

On a related note, what would happen if X had an attribute that was all zeros?

[lanzagar]

Exactly, that is why now everything is hstacked and it should work no matter what kind of metas there are.
Before, there was an if condition if np.any(data.metas): which not only failed for no metas, but also for all-zero metas, in which case they were not hstacked at all. (Probably the if should have checked if data.domain.metas) But no idea why the if was necessary at all...

[markotoplak]

My stupidity, I read this patch backwards. :D