Use median in histogram

src/report/reporters/histogram/abscissa.js

@@ -3,7 +3,7 @@ import { separatorColor } from '../../utils/colors.js'
 import { TICK_MIDDLE, HORIZONTAL_LINE } from './characters.js'
 
 // Retrieve the horizontal line and the abscissa below the main content.
-// Includes the tick above the mean positions and their labels.
+// Includes the tick above the median and its label.
 export const getAbscissa = function (width, positions) {
   const bottomLine = getBottomLine(width, positions)
   const labels = getLabels(width, positions)

src/report/reporters/histogram/content.js

@@ -1,5 +1,4 @@
 import { getAbscissa } from './abscissa.js'
-import { getMeanPositions } from './positions.js'
 import { getHistogramRows } from './rows.js'
 
 // Retrieve histogram main content
@@ -10,13 +9,16 @@ export const getContent = function ({
   width,
   mini,
 }) {
-  const { positions, meanIndex, meanMaxWidth } = getMeanPositions(stats, width)
+  const { positions, medianIndex, medianMaxWidth } = getMedianPositions(
+    stats,
+    width,
+  )
   const rows = getHistogramRows({
     histogram,
     width,
     height,
-    meanIndex,
-    meanMaxWidth,
+    medianIndex,
+    medianMaxWidth,
   })
 
   if (mini) {
@@ -27,3 +29,16 @@ export const getContent = function ({
   return `${rows}
 ${abscissa}`
 }
+
+// Compute positions of the median tick.
+// When `histogram` has a single item, it is in the first bucket.
+// Also compute the maximum width between the median and either the start or end
+// Also computes `medianIndex|medianMaxWidth` used for the color gradient.
+const getMedianPositions = function ({ median, min, max }, width) {
+  const medianPercentage =
+    max.raw === min.raw ? 0 : (median.raw - min.raw) / (max.raw - min.raw)
+  const medianIndex = Math.round((width - 1) * medianPercentage)
+  const positions = [{ ...median, index: medianIndex }]
+  const medianMaxWidth = Math.max(medianIndex, width - 1 - medianIndex)
+  return { positions, medianIndex, medianMaxWidth }
+}

src/report/reporters/histogram/main.js

@@ -40,14 +40,17 @@ const getContentWidth = function (combinations, mini, screenWidth) {
 
 const serializeHistogram = function ({
   combination,
-  combination: { stats },
+  combination: {
+    stats,
+    stats: { median },
+  },
   width,
   height,
   mini,
 }) {
   const titleBlock = getTitleBlock(combination, height, mini)
 
-  if (hasLowLoops(stats)) {
+  if (median === undefined) {
     return titleBlock
   }
 
@@ -57,9 +60,4 @@ const serializeHistogram = function ({
   return concatBlocks([titleBlock, minBlock, content, maxBlock])
 }
 
-// When using `showPrecision` and not enough loops are available.
-const hasLowLoops = function ({ mean, meanMin }) {
-  return mean === undefined && meanMin === undefined
-}
-
-export const histogram = { reportTerminal }
+export const histogram = { reportTerminal, capabilities: { debugStats: true } }

src/report/reporters/histogram/rows.js

@@ -12,14 +12,14 @@ export const getHistogramRows = function ({
   histogram,
   width,
   height,
-  meanIndex,
-  meanMaxWidth,
+  medianIndex,
+  medianMaxWidth,
 }) {
   const frequencies = getFrequencies(histogram, width)
   const columns = getHistogramColumns({
     frequencies,
-    meanIndex,
-    meanMaxWidth,
+    medianIndex,
+    medianMaxWidth,
     height,
   })
   return Array.from({ length: height }, (_, index) =>
@@ -30,13 +30,17 @@ export const getHistogramRows = function ({
 // Computes the terminal height of each column for reporting.
 const getHistogramColumns = function ({
   frequencies,
-  meanIndex,
-  meanMaxWidth,
+  medianIndex,
+  medianMaxWidth,
   height,
 }) {
   const maxHeight = getMaxHeight(frequencies, height)
   return frequencies.map(
-    getHistogramColumn.bind(undefined, { maxHeight, meanIndex, meanMaxWidth }),
+    getHistogramColumn.bind(undefined, {
+      maxHeight,
+      medianIndex,
+      medianMaxWidth,
+    }),
   )
 }
 
@@ -49,7 +53,7 @@ const getMaxHeight = function (frequencies, height) {
 // `heightLevel` is the integer part (full character) and `charIndex` is the
 // fractional part (final character on top of column).
 const getHistogramColumn = function (
-  { maxHeight, meanIndex, meanMaxWidth },
+  { maxHeight, medianIndex, medianMaxWidth },
   frequency,
   columnIndex,
 ) {
@@ -58,14 +62,16 @@ const getHistogramColumn = function (
   const charIndex = Math.ceil(
     (columnHeight - heightLevel) * (HISTOGRAM_CHARS.length - 1),
   )
-  const color = getColumnColor(columnIndex, meanIndex, meanMaxWidth)
+  const color = getColumnColor(columnIndex, medianIndex, medianMaxWidth)
   return { heightLevel, charIndex, color }
 }
 
 // Computes the column gradient color.
-const getColumnColor = function (columnIndex, meanIndex, meanMaxWidth) {
+const getColumnColor = function (columnIndex, medianIndex, medianMaxWidth) {
   const colorPercentage =
-    meanMaxWidth === 0 ? 0 : Math.abs(meanIndex - columnIndex) / meanMaxWidth
+    medianMaxWidth === 0
+      ? 0
+      : Math.abs(medianIndex - columnIndex) / medianMaxWidth
   return graphGradientColor(colorPercentage)
 }