[ML] Fixes missing y-axis description for rare chart.

x-pack/plugins/ml/public/explorer/explorer_charts/__mocks__/mock_series_config_rare.json

@@ -0,0 +1,49 @@
+{
+  "jobId": "ffb-rare-url-0921",
+  "detectorIndex": 0,
+  "metricFunction": "count",
+  "timeField": "@timestamp",
+  "interval": "15m",
+  "datafeedConfig": {
+    "datafeed_id": "datafeed-ffb-rare-url-0921",
+    "job_id": "ffb-rare-url-0921",
+    "query_delay": "115433ms",
+    "indices": [
+      "filebeat-6.0.0-2017-nginx-elasticco-anon"
+    ],
+    "types": [],
+    "query": {
+      "match_all": {
+        "boost": 1
+      }
+    },
+    "scroll_size": 1000,
+    "chunking_config": {
+      "mode": "auto"
+    },
+    "state": "stopped"
+  },
+  "functionDescription": "rare",
+  "bucketSpanSeconds": 900,
+  "detectorLabel": "rare by \"nginx.access.url\"",
+  "entityFields": [
+    {
+      "fieldName": "nginx.access.url",
+      "fieldValue": "/?node=4.1.1,5,7",
+      "fieldType": "by"
+    }
+  ],
+  "infoTooltip": {
+    "jobId": "ffb-rare-url-0921",
+    "aggregationInterval": "15m",
+    "chartFunction": "count",
+    "entityFields": [
+      {
+        "fieldName": "nginx.access.url",
+        "fieldValue": "/?node=4.1.1,5,7"
+      }
+    ]
+  },
+  "loading": true,
+  "chartData": null
+}

x-pack/plugins/ml/public/explorer/explorer_charts/components/explorer_chart_label/explorer_chart_label.js

@@ -65,7 +65,7 @@ export function ExplorerChartLabel({ detectorLabel, entityFields, infoTooltip, w
   );
 }
 ExplorerChartLabel.propTypes = {
-  detectorLabel: PropTypes.string.isRequired,
+  detectorLabel: PropTypes.object.isRequired,
   entityFields: PropTypes.arrayOf(ExplorerChartLabelBadge.propTypes.entity),
   infoTooltip: PropTypes.object.isRequired,
   wrapLabel: PropTypes.bool

x-pack/plugins/ml/public/explorer/explorer_charts/explorer_charts_container.js

@@ -57,13 +57,25 @@ function ExplorerChartContainer({
   } = series;
 
   const chartType = getChartType(series);
+  let DetectorLabel = <React.Fragment>{detectorLabel}</React.Fragment>;
+
+  if (chartType === CHART_TYPE.EVENT_DISTRIBUTION) {
+    const byField = series.entityFields.find(d => d.fieldType === 'by');
+    if (typeof byField !== 'undefined') {
+      DetectorLabel = (
+        <React.Fragment>
+          {detectorLabel}<br />y-axis event distribution split by &quot;{byField.fieldName}&quot;
+        </React.Fragment>
+      );
+    }
+  }
 
   return (
     <React.Fragment>
       <EuiFlexGroup justifyContent="spaceBetween">
         <EuiFlexItem grow={false}>
           <ExplorerChartLabel
-            detectorLabel={detectorLabel}
+            detectorLabel={DetectorLabel}
             entityFields={entityFields}
             infoTooltip={{ ...series.infoTooltip, chartType }}
             wrapLabel={wrapLabel}

x-pack/plugins/ml/public/explorer/explorer_charts/explorer_charts_container.test.js

@@ -6,6 +6,7 @@
 
 import { chartData } from './__mocks__/mock_chart_data';
 import seriesConfig from './__mocks__/mock_series_config_filebeat.json';
+import seriesConfigRare from './__mocks__/mock_series_config_rare.json';
 
 // Mock TimeBuckets and mlFieldFormatService, they don't play well
 // with the jest based test setup yet.
@@ -80,6 +81,7 @@ describe('ExplorerChartsContainer', () => {
 
   const mockedGetBBox = { x: 0, y: -11.5, width: 12.1875, height: 14.5 };
   const originalGetBBox = SVGElement.prototype.getBBox;
+  const rareChartUniqueString = 'y-axis event distribution split by';
   beforeEach(() => SVGElement.prototype.getBBox = () => mockedGetBBox);
   afterEach(() => (SVGElement.prototype.getBBox = originalGetBBox));
 
@@ -111,5 +113,29 @@ describe('ExplorerChartsContainer', () => {
     // We test child components with snapshots separately
     // so we just do some high level sanity check here.
     expect(wrapper.find('.ml-explorer-chart-container').children()).toHaveLength(2);
+
+    // Check if the additional y-axis information for rare charts is not part of the chart
+    expect(wrapper.html().search(rareChartUniqueString)).toBe(-1);
+  });
+
+  test('Initialization with rare detector', () => {
+    const wrapper = mount(<ExplorerChartsContainer
+      seriesToPlot={[{
+        ...seriesConfigRare,
+        chartData,
+        chartLimits: chartLimits(chartData)
+      }]}
+      chartsPerRow={1}
+      tooManyBuckets={false}
+      mlSelectSeverityService={mlSelectSeverityServiceMock}
+      mlChartTooltipService={mlChartTooltipService}
+    />);
+
+    // We test child components with snapshots separately
+    // so we just do some high level sanity check here.
+    expect(wrapper.find('.ml-explorer-chart-container').children()).toHaveLength(2);
+
+    // Check if the additional y-axis information for rare charts is part of the chart
+    expect(wrapper.html().search(rareChartUniqueString)).toBeGreaterThan(0);
   });
 });

x-pack/plugins/ml/public/util/chart_utils.js

@@ -318,7 +318,7 @@ export function removeLabelOverlap(axis, startTimeMs, tickInterval, width) {
     const fn = function (ts) {
       const filteredTicks = axis.selectAll('.tick').filter(d => d === ts);
 
-      if (filteredTicks[0].length === 0) {
+      if (filteredTicks.length === 0 || filteredTicks[0].length === 0) {
         return false;
       }