@turf/isobands and @turf/isolines check pointGrid input is actually gridded already#2927
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@turf/isobands and @turf/isolines check pointGrid input is actually gridded already#2927
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smallsaucepan
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Aug 31, 2025
packages/turf-isobands/index.ts
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| * @function | ||
| * @param {FeatureCollection<Point>} pointGrid input points - must be square or rectangular | ||
| * @param {FeatureCollection<Point>} pointGrid input points - must be square or rectangular and already gridded |
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Is there a clearer way to express this? Maybe cribbing from the comment where we actually do the check:
must be square or rectangular, and already gridded. That is, have consistent x and y dimensions, and be at least 2x2 in size.
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| // Isoline methods | ||
| const matrix = gridToMatrix(pointGrid, { zProperty: zProperty, flip: true }); | ||
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We do really need to find a way to share common code internally 😅
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We were seeing some issues filed around these methods not working as expected. After looking at the data it appears that the pointGrid input is not always evenly spaced gridded points. When this happens
gridToMatrix()results in an unusable result. The matrix is either not large enough to ever make any cells for marchingsquares, or of inconsistent dimensions due to not reusing the same latitudes across points (even just a slight discrepancy in the values will cause an issue).This adds explicit checks for this condition, and slightly clarifies the docs on what we're expecting to be passed in. I'm open to improvements in the wording here for clarity.
Fixes #2509, #2081