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[BUG]: `sankey`: `node.x` / `node.y` of `0` is ignored

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
75/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
d3, javascript
Domain
data-visualization, frontend

Research direction

Start in src/traces/sankey/render.js at the “Force node position” loop and check how it tests trace.node.x[p] and trace.node.y[p] for missing values. Reproduce with the supplied Plotly.newPlot example using arrangement: 'fixed'. Done when coordinates of 0 are respected and the sankey_x_y_with_arrows.json mock baseline is updated as needed.

Written by the indexing model from the issue text.

Description

bug P3 size: 1
Description

Node coordinates of 0 for node.x or node.yare ignored and the node gets positioned automatically.

Screenshots

With 0 coords:

Image

With close to 0 coords:

Image
Steps to reproduce
  • Open Plotly devtools and paste the following into browser devtools:
Plotly.newPlot('g', [{
  type: 'sankey',
  arrangement: 'fixed',
  node: {label: ['a', 'b', 'c'], x: [0, 0.5, 0.8], y: [0, 0, 0.7]},
  link: {source: [0, 1], target: [1, 2], value: [1, 1]}
}], {margin: {l: 0, r: 0, t: 0, b: 0}});
  • Note that the center of a is not in the top left corner of the plot
Notes
  • This issue stems from the fact that the "Force node position" loop in src/traces/sankey/render.js uses a truthy test (if(trace.node.x[p] && trace.node.y[p])), and 0 is falsy
  • The fix is to change the test for missing values to != null
  • The mock sankey_x_y_with_arrows.json sets y: [0, 0, 0], so the fix changes its baseline
  • Discovered while working on #7826
Dominant language
JavaScript
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Merged PRs (30d)
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