HParams: Add new selector factory to get runs from experiment ids (#6360)

## Motivation for features / changes
As part of the effort to bring hparams to the time series dashboard a
handful of new selectors need to be created. In particular I will be
creating a new one to handle runs filtering by moving the logic out of
the runs_table_container into the selector layer.
This will ensure filtered runs are consistent across the dashboard.

## Technical description of changes
This new selector is not meaningfully different from the existing one
but the factory allows it to be called with an encapsulated experiment
id.

Author: rileyajones

tensorboard/webapp/runs/store/runs_selectors.ts

@@ -79,6 +79,22 @@ export const getRuns = createSelector(
   }
 );
 
+export const getRunsFromExperimentIds = (experimentIds: string[]) =>
+  createSelector(
+    getDataState,
+    (state: RunsDataState): Array<Run & {experimentId: string}> => {
+      return experimentIds.reduce((runs, experimentId) => {
+        (state.runIds[experimentId] || [])
+          .filter((id) => Boolean(state.runMetadata[id]))
+          .forEach((runId) => {
+            runs.push({...state.runMetadata[runId], experimentId});
+          });
+
+        return runs;
+      }, [] as Array<Run & {experimentId: string}>);
+    }
+  );
+
 /**
  * Returns Observable that emits runs list for an experiment.
  */

tensorboard/webapp/runs/store/runs_selectors_test.ts

@@ -176,6 +176,57 @@ describe('runs_selectors', () => {
     });
   });
 
+  describe('#getRunsFromExperimentIds', () => {
+    it('returns runs', () => {
+      const state = buildStateFromRunsState(
+        buildRunsState({
+          runIds: {
+            eid: ['run1'],
+          },
+          runMetadata: {
+            run1: buildRun({id: 'run1'}),
+          },
+        })
+      );
+      expect(selectors.getRunsFromExperimentIds(['eid'])(state)).toEqual([
+        {
+          ...buildRun({
+            id: 'run1',
+          }),
+          experimentId: 'eid',
+        },
+      ]);
+    });
+
+    it('returns runs for the ones that has metadata', () => {
+      const state = buildStateFromRunsState(
+        buildRunsState({
+          runIds: {
+            eid: ['run1', 'run2'],
+          },
+          runMetadata: {
+            run1: buildRun({id: 'run1'}),
+          },
+        })
+      );
+      expect(selectors.getRunsFromExperimentIds(['eid'])(state)).toEqual([
+        {
+          ...buildRun({
+            id: 'run1',
+          }),
+          experimentId: 'eid',
+        },
+      ]);
+    });
+
+    it('returns empty list if experiment id does not exist', () => {
+      const state = buildStateFromRunsState(buildRunsState());
+      expect(
+        selectors.getRunsFromExperimentIds(['i_do_not_exist'])(state)
+      ).toEqual([]);
+    });
+  });
+
   describe('#getRunIdsForExperiment', () => {
     beforeEach(() => {
       // Clear the memoization.