fix(Sankey): prevent NaN node positions when link values sum to zero by Mridul012 · Pull Request #7185 · recharts/recharts

Mridul012 · 2026-03-29T13:17:48Z

Summary

Fixes a division-by-zero issue in Sankey layout that can produce NaN node positions when link values sum to 0.

Problem

In relaxLeftToRight and relaxRightToLeft, node positions are computed using:

weightedSum / sourceSum
weightedSum / targetSum

When sourceSum or targetSum is 0, this results in NaN, which propagates and breaks the layout.

Fix

Added guards to handle zero sums:

Fallback to centerY(node) when sourceSum === 0
Fallback to centerY(node) when targetSum === 0

Tests

Added a regression test to ensure:

No NaN node positions are produced when link values are zero

Impact

Prevents layout corruption in edge cases
No impact on normal datasets

Summary by CodeRabbit

Bug Fixes
- Improved Sankey chart handling of zero-value links to prevent invalid layout values and ensure stable rendering (nodes with no flow are omitted while links remain valid).
Tests
- Added tests covering zero-value link scenarios, asserting node rendering rules and that generated path data contains no invalid numbers.

coderabbitai · 2026-03-29T13:18:13Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 0937d614-bdc1-4e7d-aa75-3cb291553568

📥 Commits

Reviewing files that changed from the base of the PR and between a0fe1bb and eab9311.

📒 Files selected for processing (2)

src/chart/Sankey.tsx
test/chart/Sankey.spec.tsx

🚧 Files skipped from review as they are similar to previous changes (2)

test/chart/Sankey.spec.tsx
src/chart/Sankey.tsx

Walkthrough

Guard against division-by-zero in Sankey layout: three methods in src/chart/Sankey.tsx now fallback to centerY(node) or clamp yRatio when depth-level sums are zero. Tests added to validate rendering with zero-valued links.

Changes

Cohort / File(s)	Summary
Sankey layout calculation guards `src/chart/Sankey.tsx`	Added zero-sum checks in `updateYOfTree`, `relaxLeftToRight`, and `relaxRightToLeft`; use `Infinity`/clamp semantics for `yRatio` and `centerY(node)` as fallback when sums are zero to avoid `Infinity`/`NaN`.
Sankey zero-value tests `test/chart/Sankey.spec.tsx`	Added tests covering all-zero `links[].value` and mixed zero/positive scenarios; assert node/link rendering behavior and that link path `d` and `stroke-width` are finite and contain no `NaN`.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Suggested reviewers

PavelVanecek
ckifer

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description covers the problem, fix, and tests, but is missing several required template sections: Related Issue link, detailed testing methodology, Screenshots section, Types of changes checkboxes, and completion of the Checklist items.	Add the missing template sections: link the related issue, describe testing environment and test execution details, complete the Types of changes and Checklist sections with appropriate checkmarks.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the primary change: fixing NaN node positions in Sankey when link values sum to zero, matching the code modifications in updateYOfTree, relaxLeftToRight, and relaxRightToLeft.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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coderabbitai

Actionable comments posted: 1

🧹 Nitpick comments (1)

test/chart/Sankey.spec.tsx (1)
741-767: Good regression test for the all-zero case.

The test correctly validates that NaN values don't appear in link paths when all link values are zero.

Consider adding a companion test with mixed link values (e.g., { source: 0, target: 1, value: 100 }, { source: 1, target: 2, value: 0 }) to ensure nodes with positive values still render correctly. This would guard against regressions in the yRatio calculation for datasets where only some links have zero values.

,
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In `@test/chart/Sankey.spec.tsx` around lines 741 - 767, Add a companion test to
Sankey.spec.tsx that renders the Sankey component with mixed link values (e.g.,
links [{ source: 0, target: 1, value: 100 }, { source: 1, target: 2, value: 0
}]) and assert that nodes with positive aggregated value render (query
'.recharts-sankey-node' and expect length > 0), links render without NaN in
their path 'd' attribute and have finite 'stroke-width', so we validate the
yRatio/layout logic handles mixed zero/non-zero link values correctly when using
the Sankey component.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/chart/Sankey.tsx`:
- Around line 207-212: The current yRatio calculation returns 0 for any depth
with sum===0 which makes Math.min pick 0 and collapse positive-valued nodes;
instead, when mapping depthTree use Infinity as the fallback for sum===0 so
Math.min correctly ignores empty depths (use sumBy, getValue, nodePadding,
height in that mapping), then after computing yRatio = Math.min(...candidates)
add a special case: if yRatio === Infinity set yRatio = 0 (handles the all-zero
case). This preserves previous behavior for mixed and all-zero scenarios.

---

Nitpick comments:
In `@test/chart/Sankey.spec.tsx`:
- Around line 741-767: Add a companion test to Sankey.spec.tsx that renders the
Sankey component with mixed link values (e.g., links [{ source: 0, target: 1,
value: 100 }, { source: 1, target: 2, value: 0 }]) and assert that nodes with
positive aggregated value render (query '.recharts-sankey-node' and expect
length > 0), links render without NaN in their path 'd' attribute and have
finite 'stroke-width', so we validate the yRatio/layout logic handles mixed
zero/non-zero link values correctly when using the Sankey component.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 3b81251a-15a3-4d1c-bb0e-e3ab3aa4eb92

📥 Commits

Reviewing files that changed from the base of the PR and between fc96239 and a0fe1bb.

📒 Files selected for processing (2)

src/chart/Sankey.tsx
test/chart/Sankey.spec.tsx

… positive nodes

codecov · 2026-03-30T05:32:00Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.06%. Comparing base (fc96239) to head (eab9311).
⚠️ Report is 15 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7185   +/-   ##
=======================================
  Coverage   89.06%   89.06%           
=======================================
  Files         539      539           
  Lines       41011    41017    +6     
  Branches     5553     5557    +4     
=======================================
+ Hits        36527    36533    +6     
  Misses       4476     4476           
  Partials        8        8

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codecov · 2026-03-30T06:58:37Z

Bundle Report

Changes will increase total bundle size by 432 bytes (0.01%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
recharts/bundle-cjs	1.3MB	177 bytes (0.01%) ⬆️
recharts/bundle-es6	1.13MB	177 bytes (0.02%) ⬆️
recharts/bundle-umd	547.98kB	78 bytes (0.01%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: recharts/bundle-umd

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`Recharts.js`	78 bytes	547.98kB	0.01%

view changes for bundle: recharts/bundle-cjs

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`chart/Sankey.js`	177 bytes	32.24kB	0.55%

view changes for bundle: recharts/bundle-es6

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`chart/Sankey.js`	177 bytes	30.48kB	0.58%

Mridul012 · 2026-03-31T06:17:28Z

Thanks for the review, Please let me know if any further changes are needed.

fix(sankey): prevent NaN and Infinity when all node/link values are 0

a0fe1bb

coderabbitai Bot reviewed Mar 29, 2026

View reviewed changes

Comment thread src/chart/Sankey.tsx Outdated

fix(sankey): use Infinity for yRatio when sum is 0 to avoid squashing…

eab9311

… positive nodes

ckifer approved these changes Mar 30, 2026

View reviewed changes

ckifer merged commit 0f5689c into recharts:main Apr 3, 2026
52 checks passed

coderabbitai Bot mentioned this pull request Jun 18, 2026

fix: avoid Sankey nodes overlapping skipped-depth links #7471

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fix(Sankey): prevent NaN node positions when link values sum to zero#7185

fix(Sankey): prevent NaN node positions when link values sum to zero#7185
ckifer merged 2 commits into
recharts:mainfrom
Mridul012:fix/sankey-zero-division

Mridul012 commented Mar 29, 2026 •

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Summary

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Tests

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