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[BUG]: `shape.pattern` for bar trace causes color and pattern to be applied to wrong traces in unified hover tooltip

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
70/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
javascript

Research direction

Start with the CodePen reproduction and the Plotly.newPlot configuration using hovermode: 'x unified', marker.color, and marker.pattern. Trace how the unified hover tooltip chooses each bar's swatch, then verify that hovering over A and B shows the matching color and pattern for each bar.

Written by the indexing model from the issue text.

Description

bug good for agent P3 size: 1
Description

When shape.pattern is provided as an array to a bar trace, the first bar's pattern (and color!) are incorrectly applied to both bars in the hovermode: 'x unified' hover tooltip.

Expected: Swatch in hover tooltip should match color and pattern of bar which is being hovered over.

Actual: Swatch in hover tooltip matches color and pattern of first bar in trace, even when hovering over the second bar.

When shape.pattern is not provided, each hover tooltip correctly shows the color of the bar that's being hovered over.

Screenshots/Video
Image
Steps to reproduce

Codepen: https://codepen.io/emilykl-code/pen/azJvXPy

Code:

var fig = {
  "data": [
    {
      "marker": {
        "color": ["red", "purple"],
        "pattern": {"shape": ["/", ""]}
      },
      "textposition": "outside",
      "x": ["A", "B"],
      "y": [1, 2],
      "type": "bar"
    }
  ],
  "layout": {
    "hovermode": "x unified",
    "title": {
      "text": "Hover over 'B' to see wrong color and pattern"
    }}
};
Plotly.newPlot("div1", fig.data, fig.layout);
Notes

First reported in plotly.py by https://github.com/plotly/plotly.py/issues/4882

Dominant language
JavaScript
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Merged PRs (30d)
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