Support divergent color ramps #912

nakul-py · 2025-08-29T14:37:31Z

Description

Addresses #881

Currently, Color Ramp Type only supports Divergent colors such as balance, delta , curl, diff and tarn so other colormaps are still show type unknown. Enable users to set a min and max value and also get self-populated min max values for the colormap.
Also updates Color Ramp when user setted to reverse.

Checklist

PR has a descriptive title and content.
PR description contains references to any issues the PR resolves, e.g. Resolves #XXX.
PR has one of the labels: documentation, bug, enhancement, feature, maintenance
Checks are passing.
Failing lint checks can be resolved with:
- pre-commit run --all-files
- jlpm run lint

📚 Documentation preview: https://jupytergis--912.org.readthedocs.build/en/912/
💡 JupyterLite preview: https://jupytergis--912.org.readthedocs.build/en/912/lite

github-actions · 2025-08-29T14:37:40Z

👈 Launch a Binder on branch nakul-py/jupytergis/divergent

github-actions · 2025-08-29T14:49:11Z

Integration tests report: appsharing.space

nakul-py

cmocean's "balance" is cool :)

packages/base/src/dialogs/symbology/colorRampUtils.ts

mfisher87

Hey Nakul! This looks really good so far! I have some thoughts on the implementation details, most importantly around saving the min & max into the project file as symbologyState.min, symbologyState.max and updating singleband pseudocolor (for raster data) to share the same behavior. We can definitely share a common component!

packages/base/src/dialogs/symbology/colorRampUtils.ts

packages/base/src/dialogs/symbology/components/color_ramp/ColorRamp.tsx

packages/base/src/dialogs/symbology/vector_layer/types/Categorized.tsx

packages/base/src/dialogs/symbology/symbologyUtils.ts

packages/base/src/dialogs/symbology/components/color_ramp/ColorRamp.tsx

packages/base/src/panelview/components/legendItem.tsx

mfisher87 · 2025-09-10T16:43:47Z

Hey @nakul-py I'm a bit overwhelmed with interviewing folks for an internship program. I may be a bit delayed!

Co-authored-by: Nakul Verma <nakulverma.py@gmail.com>

mfisher87

Nakul and I worked on this together for a little bit today. Just leaving some thoughts we talked about -- I'll get to a more comprehensive review on Monday!

packages/base/src/dialogs/symbology/colorRampUtils.ts

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampControls.tsx

packages/base/src/dialogs/symbology/hooks/useGetBandInfo.ts

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampControls.tsx

packages/base/src/dialogs/symbology/components/color_ramp/ColorRamp.tsx

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampValueControls.tsx

packages/base/src/dialogs/symbology/tiff_layer/types/SingleBandPseudoColor.tsx

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampValueControls.tsx

packages/base/src/dialogs/symbology/tiff_layer/components/BandRow.tsx

…g as expected dataMin and dataMax should be attributes of the `source`, not the layer/symbology. This only impacts performance, so let's punt it for later.

These are different things! The data minimum and maximum are attributes of the data, and symbology min/max are user preference.

packages/base/src/dialogs/symbology/hooks/useGetSingleBandInfo.ts

mfisher87 · 2025-11-19T16:34:35Z

Looks like we have a bug where changing the band number in the singleband symbology menu doesn't change the rendered output. The identify tool indicates that we should see a difference between the bands!

mfisher87 · 2025-11-19T16:05:15Z

packages/base/src/dialogs/symbology/hooks/useGetSingleBandInfo.ts

+      let dataMax = image.fileDirectory.STATISTICS_MAXIMUM;
+
+      if (dataMin === undefined || dataMax === undefined) {
+        // 2. Try smallest overview if available


Suggested change

// 2. Try smallest overview if available

// 2. Try smallest overview if available

// A consequence of this method is that we will almost never find the **true** minimum and maximum for the whole raster, as overviews are aggregate data, averaging groups of grid cells to calculate lower-resolution grid cells. However, calculating the minimum and maximum from the entire dataset may be prohibitively expensive on CPU and memory!

mfisher87 · 2025-11-19T16:07:08Z

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampSelector.tsx

        ))}
      </div>
+
+      <div className="jp-gis-symbology-row">


Refactor: Moved reverse checkbox into the selector because whether the colormap is reversed is part of selecting a colormap. Helped us organize logic related to this PR's goal more easily.

mfisher87 · 2025-11-19T16:14:08Z

packages/base/src/types.ts

+  picnic: 11,
+  'rainbow-soft': 11,
+  cubehelix: 16,
+};


This isn't a type, let's move it to colorRamps.ts?

mfisher87 · 2025-11-19T16:18:18Z

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampControls.tsx

@@ -14,15 +18,28 @@ interface IColorRampProps {
    numberOfShades: string,
    selectedRamp: string,
    setIsLoading: (isLoading: boolean) => void,
+    criticalValue?: number,


Since this is for display only, classifyFunc doesn't need to receive it as an argument anymore. Let's remove it!

Suggested change

criticalValue?: number,

mfisher87 · 2025-11-19T16:54:54Z

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampControls.tsx

+    // Typeguard: This should never happen
+    return;
+  }
+  const scaledCritical =


Suggested change

const scaledCritical =

// Get the critical value (divergence point in a divergent colormap) as a data value using equal interval interpolation.

// This is only used if equal interval classification mode is selected.

const criticalDataValue =

mfisher87 · 2025-11-19T16:57:16Z

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampControls.tsx

+      ? minValue + rampDef.criticalValue * (maxValue - minValue)
+      : undefined;
+
+  useEffect(() => {


Suggested change

useEffect(() => {

// update shared model symbology state from component state

useEffect(() => {

mfisher87 · 2025-11-19T17:01:13Z

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampControls.tsx

+    layerParams.symbologyState = {
+      ...layerParams.symbologyState,
+      dataMin,
+      dataMax,


dataMin and dataMax aren't being saved to the symbology state (we can see that the JSON isn't being updated). This is because we need to call a function to update the shared model; if we only assign to it, it won't update the model. I don't have that function name at hand and have to jump on to a meeting. Let me know if you have trouble finding it!

Though in my testing, things seem to be working well, so I wonder if this whole effect can be deleted and things will still work?

Supporting divergent colomaps

78e9966

nakul-py added 2 commits August 29, 2025 20:48

critical value only for divergent

63bcb15

Divergent with min-max

e9ecb40

nakul-py changed the title ~~Wip: Supporting divergent colomaps with critical value~~ Supporting divergent colomaps with critical value Sep 2, 2025

nakul-py marked this pull request as ready for review September 2, 2025 12:16

nakul-py commented Sep 2, 2025

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packages/base/src/dialogs/symbology/colorRampUtils.ts Outdated Show resolved Hide resolved

mfisher87 added the enhancement New feature or request label Sep 3, 2025

mfisher87 requested changes Sep 3, 2025

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mfisher87 changed the title ~~Supporting divergent colomaps with critical value~~ Support divergent color ramps Sep 3, 2025

mfisher87 reviewed Sep 3, 2025

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packages/base/src/panelview/components/legendItem.tsx Outdated Show resolved Hide resolved

mfisher87 requested a review from arjxn-py September 3, 2025 16:13

nakul-py marked this pull request as draft September 5, 2025 08:53

nakul-py added 5 commits September 5, 2025 14:31

changes

2e2f37b

lint fix

67faef4

support singleband psuedocolor

1af0c01

pre-populating values

19ed962

making radius work wit min and max

dbeb780

nakul-py marked this pull request as ready for review September 9, 2025 11:02

nakul-py requested a review from mfisher87 September 9, 2025 11:02

gives colors a sequance

c1fbede

Simplify call to useColorMapList effect

b478a85

Co-authored-by: Nakul Verma <nakulverma.py@gmail.com>

mfisher87 force-pushed the divergent branch from 3a488a0 to b478a85 Compare September 12, 2025 15:32

Remove type assertion

df7df8f

Co-authored-by: Nakul Verma <nakulverma.py@gmail.com>

mfisher87 reviewed Sep 12, 2025

View reviewed changes

packages/base/src/dialogs/symbology/colorRampUtils.ts Outdated Show resolved Hide resolved

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampControls.tsx Outdated Show resolved Hide resolved

geojupyter-pr-triage bot added this to JupyterGIS PR triage Sep 12, 2025

nakul-py force-pushed the divergent branch from 835794a to c067f57 Compare September 14, 2025 08:37

Update selectedRamp state initialization

4c86aaf

nakul-py requested a review from mfisher87 October 7, 2025 10:28

mfisher87 reviewed Oct 10, 2025

View reviewed changes

Adding seperate hook files for Singleband and Multiband Colors.

2e0209e

nakul-py requested a review from mfisher87 October 13, 2025 08:45

nakul-py commented Oct 13, 2025

View reviewed changes

packages/base/src/dialogs/symbology/hooks/useGetBandInfo.ts Show resolved Hide resolved

refactor

372b9c5

mfisher87 reviewed Oct 15, 2025

View reviewed changes

packages/base/src/dialogs/symbology/tiff_layer/types/SingleBandPseudoColor.tsx Show resolved Hide resolved

mfisher87 reviewed Oct 15, 2025

View reviewed changes

packages/base/src/dialogs/symbology/components/color_ramp/ColorRampValueControls.tsx Show resolved Hide resolved

Restore empty tag for easier diff reading

3d07f7b

mfisher87 reviewed Oct 15, 2025

View reviewed changes

packages/base/src/dialogs/symbology/tiff_layer/components/BandRow.tsx Show resolved Hide resolved

mfisher87 added 2 commits October 15, 2025 09:21

Remove dataMin/Max from symbologyState and note that it's not updatin…

5370f3e

…g as expected dataMin and dataMax should be attributes of the `source`, not the layer/symbology. This only impacts performance, so let's punt it for later.

Avoid loading the dataMin/Max from symbology min/max

1cb0b92

These are different things! The data minimum and maximum are attributes of the data, and symbology min/max are user preference.

mfisher87 reviewed Oct 15, 2025

View reviewed changes

packages/base/src/dialogs/symbology/hooks/useGetSingleBandInfo.ts Outdated Show resolved Hide resolved

nakul-py added 2 commits October 16, 2025 18:48

Refactoring...

cf5fd26

Selectedband selection fix

1747e6e

nakul-py mentioned this pull request Oct 17, 2025

Singleband pseudocolor band selector doesn't respect user selection #958

Open

nakul-py requested a review from mfisher87 October 17, 2025 06:12

mfisher87 mentioned this pull request Oct 17, 2025

Add support for saving color stops in symbologyState #949

Open

4 tasks

nakul-py added 2 commits November 7, 2025 19:14

Resolving Conflicts

657aba6

Merge branch 'main' into divergent

612d0fa

mfisher87 mentioned this pull request Nov 13, 2025

Store marker color as a layer attribute instead of a source attribute #987

Open

nakul-py force-pushed the divergent branch from a54c7e4 to 612d0fa Compare November 15, 2025 05:43

nakul-py added 3 commits November 15, 2025 11:50

Resolving conflicts while Merging branch 'main' into divergent

10dc8b4

Fixing infinite loop bug on ramp and classes

673a777

lint

7a5b754

mfisher87 requested a review from martinRenou November 19, 2025 16:05

mfisher87 reviewed Nov 19, 2025

View reviewed changes

nakul-py mentioned this pull request Nov 20, 2025

Fixing SingleBand pseudocolor band selector bug #998

Open

4 tasks

	// 2. Try smallest overview if available
	// 2. Try smallest overview if available
	// A consequence of this method is that we will almost never find the true minimum and maximum for the whole raster, as overviews are aggregate data, averaging groups of grid cells to calculate lower-resolution grid cells. However, calculating the minimum and maximum from the entire dataset may be prohibitively expensive on CPU and memory!

-  const scaledCritical =
+  // Get the critical value (divergence point in a divergent colormap) as a data value using equal interval interpolation.
+  // This is only used if equal interval classification mode is selected.
+  const criticalDataValue =

	useEffect(() => {
	// update shared model symbology state from component state
	useEffect(() => {

Support divergent color ramps #912

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