changeset 241:9285f1b80990

Some reducer functions for folding StreamingResponses into a single response.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/app/services/feature-extraction/FeatureReducers.ts	Wed Apr 26 16:13:15 2017 +0100
@@ -0,0 +1,63 @@
+/**
+ * Created by lucast on 26/04/2017.
+ */
+import {StreamingResponse} from 'piper/StreamingService';
+import {Feature} from 'piper/Feature';
+import {SampleType} from 'piper';
+
+export const arrayReducer = <T>(acc: T[], val: T[]): T[] => {
+  acc.push.apply(acc, val);
+  return acc;
+};
+
+export const typedArrayReducer = (acc: Float32Array,
+                                  val: Float32Array): Float32Array => {
+  return Float32Array.of(...acc, ...val);
+};
+
+const inPlaceTypedArrayReducer = (acc: Float32Array,
+                                  val: Float32Array,
+                                  i: number): Float32Array => {
+  acc.set(val, i);
+  return acc;
+};
+
+export const streamingResponseReducer = (acc: StreamingResponse,
+                                         val: StreamingResponse,
+                                         i: number): StreamingResponse => {
+  acc.processedBlockCount = val.processedBlockCount;
+  if (acc.features.data instanceof Array &&
+    val.features.data instanceof Array) {
+    acc.features.data = arrayReducer<Feature>(
+      acc.features.data,
+      val.features.data
+    );
+  } else if (acc.features.data instanceof Float32Array &&
+    val.features.data instanceof Float32Array) {
+    const isOneSamplePerStep = acc.outputDescriptor.configured.sampleType ===
+      SampleType.OneSamplePerStep;
+    if (isOneSamplePerStep) {
+      // for one sample per step vectors we know there will be totalBlockCount
+      // number of samples - so pre-allocate the Float32Array when we know
+      // the totalBlockCount (after receiving the first feature)
+      if ( i === 1  ) {
+        const newBlock = new Float32Array(acc.totalBlockCount);
+        newBlock[0] = acc.features.data[0];
+        acc.features.data = newBlock;
+      }
+      acc.features.data = inPlaceTypedArrayReducer(
+        acc.features.data,
+        val.features.data,
+        i
+      );
+    } else { // if not OneSamplePerStep we have to make a new array each time
+      acc.features.data = typedArrayReducer(
+        acc.features.data,
+        val.features.data
+      );
+    }
+  } else {
+    throw new Error('Invalid feature output. Aborting');
+  }
+  return acc;
+};