fix: drag of dot with zero value in dot plot (#1632)

v3/src/components/graph/hooks/use-dot-plot-drag-drop.ts

@@ -1,15 +1,16 @@
+import { ScaleLinear } from "d3"
 import * as PIXI from "pixi.js"
-import { useGraphLayoutContext } from "./use-graph-layout-context"
-import { useDataDisplayAnimation } from "../../data-display/hooks/use-data-display-animation"
-import { useGraphDataConfigurationContext } from "./use-graph-data-configuration-context"
+import { useRef, useState } from "react"
 import { useDataSetContext } from "../../../hooks/use-data-set-context"
-import { ScaleLinear } from "d3"
-import { IPixiPointMetadata } from "../../data-display/pixi/pixi-points"
 import { appState } from "../../../models/app-state"
+import { ICase } from "../../../models/data/data-set-types"
+import { toNonEmptyValue } from "../../../utilities/math-utils"
 import { handleClickOnCase } from "../../data-display/data-display-utils"
 import { dataDisplayGetNumericValue } from "../../data-display/data-display-value-utils"
-import { useRef, useState } from "react"
-import { ICase } from "../../../models/data/data-set-types"
+import { useDataDisplayAnimation } from "../../data-display/hooks/use-data-display-animation"
+import { IPixiPointMetadata } from "../../data-display/pixi/pixi-points"
+import { useGraphDataConfigurationContext } from "./use-graph-data-configuration-context"
+import { useGraphLayoutContext } from "./use-graph-layout-context"
 
 export const useDotPlotDragDrop = () => {
   const layout = useGraphLayoutContext()
@@ -43,7 +44,7 @@ export const useDotPlotDragDrop = () => {
     // Record the current values, so we can change them during the drag and restore them when done
     const {selection} = dataConfig || {}
     selection?.forEach((anID: string) => {
-      const itsValue = dataDisplayGetNumericValue(dataset, anID, primaryAttrID) || undefined
+      const itsValue = toNonEmptyValue(dataDisplayGetNumericValue(dataset, anID, primaryAttrID))
       if (itsValue != null) {
         selectedDataObjects.current[anID] = itsValue
       }

v3/src/utilities/math-utils.ts

@@ -147,6 +147,9 @@ export const isValueEmpty = (value: any) => value == null || value === ""
 
 export const isValueNonEmpty = (value: any) => !isValueEmpty(value)
 
+// returns undefined for empty values, and the value itself for non-empty values
+export const toNonEmptyValue = (value: any) => isValueEmpty(value) ? undefined : value
+
 // Similar to isFiniteNumber, but looser.
 // It allows for strings that can be converted to numbers and treats Infinity and -Infinity as valid numbers.
 export const isNumber = (v: any) => isValueNonEmpty(v) && !isNaN(Number(v))