add sample size

src/plugins/comps/CompsManager.js

@@ -60,7 +60,8 @@ export default class CompsManager extends EventEmitter {
       valueToUse,
       testValue: 0,
       timeMetaData,
-      accumulateValues: false
+      accumulateValues: false,
+      sampleSize: null
     });
     this.emit('parameterAdded', this.#domainObject);
   }

src/plugins/comps/CompsMathWorker.js

@@ -83,6 +83,14 @@ function calculate(dataFrame, parameters, expression) {
       accumulatedData[referenceParameter.name].push(referenceValue);
       referenceValue = accumulatedData[referenceParameter.name];
     }
+    if (referenceParameter.sampleSize) {
+      // enforce sample size by ensuring referenceValue has the latest n elements
+      // if we don't have at least the sample size, skip this iteration
+      if (referenceValue.length < referenceParameter.sampleSize) {
+        return;
+      }
+      referenceValue = referenceValue.slice(-referenceParameter.sampleSize);
+    }
 
     const scope = {
       [referenceParameter.name]: referenceValue

src/plugins/comps/components/CompsView.vue

@@ -102,6 +102,7 @@
               ]"
             >
               <label v-if="isEditing" class="c-toggle-switch">
+                <span class="c-toggle-switch__label">Accumulate Values</span>
                 <input
                   v-model="parameter.accumulateValues"
                   type="checkbox"
@@ -111,8 +112,19 @@
                   class="c-toggle-switch__slider"
                   aria-label="Toggle Parameter Accumulation"
                 ></span>
-                <span class="c-toggle-switch__label">Accumulate Values</span>
               </label>
+
+              <span v-if="isEditing && parameter.accumulateValues" class="c-test-datum__string"
+                >Sample Size</span
+              >
+              <input
+                v-if="isEditing && parameter.accumulateValues"
+                v-model="parameter.sampleSize"
+                :aria-label="`Sample Size for ${parameter.name}`"
+                type="text"
+                class="c-input--md"
+                @change="updateParameters"
+              />
             </div>
           </span>