fixes weird legend behavior

[cnavarreteliz]

closes #103

Description

This bug was caused inside _drawLabel function of Viz.js, because that function always returns the last element.

For to solve it, I added a flag for to return the first value in the legend.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have documented all new methods.
• I have written tests for all new methods/functionality.
• I have written examples for all new methods/functionality.

[davelandry]

This logic won't always work, as the coloring of shapes is not always mapped to the highest groupBy level. For example, the user may have 3 levels of nesting, and be coloring by the second level. In that case, we would want the 2nd level to be the label (not [0]).

Here's a proposed solution: analyze the legendData array that is created in src/_drawLegend.js, and find the deepest level where all of the data points only have 1 label. Then, make the 3rd argument in _drawLabel be an optional index of the label depth requested.

[cnavarreteliz]

@davelandry I've been testing the bug and d3plus-hierarchy it's coloring by the highest groupBy level (https://jsfiddle.net/6d5ako1t/), is that a bug? Or the config is incorrect?

[davelandry]

Yes, by default it will use the highest groupBy, but here's an example where the user may specify a fill corresponding to a different level: https://jsfiddle.net/6d5ako1t/1/

[cnavarreteliz]

@davelandry it was very difficult guessing the highest level, because sometimes we had two properties at the same depth level, so I propose a mini-correction using this._depth

[davelandry]

This still does not address the original issue shown here: http://jsfiddle.net/g149pjqo/3/

To reset our conversation, there are 2 bugs that need fixing:

1. The labels should all show the correct nesting label based on where colors are assigned. For example, the default logic (this._color in Viz.js) chooses the highest grouping level (this._groupBy[0]). The solution will probably be related to either using the this._color function, or modifying it in some way (along with modifying the legendLabel function in _drawLegend.js).
2. When multiple groups get assigned the same color (because there are only a few default colors available), the legend should show all of their names separated by commas (currently it shows no label).

This all should be achievable without modifying the drawLabel function.