[FIX] OWMergeData removes table meta attributes

[AndrejaKovacic]

Issue

Fixes #3289

Description of changes

Merged data is added to original table instead of creating a new one.

Includes

• Code changes
• Tests
• Documentation

[markotoplak]

Is this changing the input data? The input data should never be modified (if any other widgets were also using the same data they would break). To support workflows, we should never modify data in place.

[lanzagar]

What @markotoplak said. And although that could be fixed by making a copy of the data first and modifying that, I don't think you should just overwrite the domain of a Table, the arrays X, Y, metas, etc. It would be too easy to end up with an inconsistent Table (the shape of X might not agree with the size of the domain, ids, ...).

[AndrejaKovacic]

I think the most appropriate solution would be to use the function from_numpy and add an option to add metadata as a parameter. I know @lanzagar disagrees with it, because there are some issues with that function, but maybe we should fix from_numpy, instead of trying to create new table here.

[janezd]

About travis errors: lint issues are obvious, while to avoid segfault in documentation, you need to rebase to today's master.

[janezd]

I don't know this code well, but judging by what I see in the Table class, I think that you should have getattr(self.data, 'name', '') and getattr(self.data, 'attributes', {}).

ids seems to be always present, so it's just table.ids = self.data.ids.

(Perhaps name and attributes are always present, too, but a lot of code does getattr for them.)

[codecov]

Codecov Report

Merging #3474 into master will increase coverage by 0.05%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3474      +/-   ##
==========================================
+ Coverage    83.5%   83.55%   +0.05%     
==========================================
  Files         367      367              
  Lines       65182    65466     +284     
==========================================
+ Hits        54429    54703     +274     
- Misses      10753    10763      +10

[codecov]

Codecov Report

Merging #3474 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3474      +/-   ##
==========================================
+ Coverage   83.57%   83.57%   +<.01%     
==========================================
  Files         367      367              
  Lines       65536    65548      +12     
==========================================
+ Hits        54769    54782      +13     
+ Misses      10767    10766       -1

[janezd]

Burning some midnight oil?

[AndrejaKovacic]

I was going to coment it's not even midnight yet. Time flies :)