[ENH] OWColor: Saving and loading color schemata

[janezd]

Issue

Resolves #4890.

Description of changes

I defined two file formats. One contains all changes done by the user, e.g.

{
    "categorical": {
        "gender": {
            "renamed_values": {
                "female": "women",
                "male": "man"
            }
        },
        "fasting blood sugar > 120": {
            "rename": "fasting blood sugar is high",
            "colors": {
                "0": "#21FF06",
                "1": "#996633"
            }
        },
        "exerc ind ang": {
            "colors": {
                "0": "#46BEFA",
                "1": "#996633"
            }
        },
        "slope peak exc ST": {
            "renamed_values": {},
            "colors": {
                "upsloping": "#FD8008",
                "flat": "#ED462F",
                "downsloping": "#AAF22B"
            }
        }
    },
    "numeric": {
        "rest SBP": {
            "colors": "linear_bgyw_20_98_c66"
        },
        "cholesterol": {
            "colors": "diverging_bwr_40_95_c42"
        },
    }
}

When loading the file, it's content does not have to exactly match the domain: redundant variables/values are ignored, and data for variables that does not appear in the file is retained as it is in the widget.

The second format contains general definitions of colors, like

{
    "female": "#FF0000",
    "1": "#996633",
    "upsloping": "#FD8008"
}

When saving, it stores the colors for values that were changed by the user, and only if the change if the same for all variables in the domain (e.g. if all "female" that are changed are changed to the same color). When loading, it changes colors for all values that appear in any variable.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #4977 into master will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #4977      +/-   ##
==========================================
+ Coverage   84.47%   84.51%   +0.03%     
==========================================
  Files         283      283              
  Lines       58344    58471     +127     
==========================================
+ Hits        49289    49414     +125     
- Misses       9055     9057       +2     

[janezd]

Note to self: remove the "general" format (in a separate commit, so we still have the code in case we need it someday).

The remaining code implements what the issue was about. The second format is not very useful, except as a workaround for copying colors assigned to one variable to all other variables. A better solution for this is to add "Copy to all" to discrete variables, but so far nobody needed it, so we won' t implement the feature, until somebody wants it badly enough.

[CLAassistant]

All committers have signed the CLA.

[ajdapretnar]

I tried testing this but I can't seem to get a working file. I tried the first file in the first comment. What am I doing wrong?

[janezd]

I may have changed the format (though I think I haven't). But why would you use the file from the comment? You can just change some colors and names, and save the file.