added MEDIAN

Author: bihmi-lb

herald-core/herald-grammar.js

@@ -24,7 +24,7 @@
         conjunctionAnd: ['AND'],
         conjunctionOr: ['OR'],
         field: ['LABEL', 'VALUE', 'UNIT', 'START', 'END', 'NUMERIC'],
-        aggregation: ['AVERAGE', 'COUNT', 'SUM', 'MIN', 'MAX', 'MOST FREQUENT'],
+        aggregation: ['AVERAGE', 'MEDIAN', 'COUNT', 'SUM', 'MIN', 'MAX', 'MOST FREQUENT'],
         selection: ['FIRST', 'LAST', 'ANY'],
         relationship: ['RATIO BETWEEN', 'DIFFERENCE BETWEEN', 'EQUALITY OF'],
         existence: ['EXISTS', 'NOT EXISTS'],

herald-core/herald-interpreter.js

@@ -422,6 +422,28 @@ function parseFilter(observations, query) {
           }
           break;
         }
+        case 'MEDIAN': {
+          let numericObservations = observations.filter(obs => obs.isNumeric);
+          if(numericObservations && numericObservations.length > 0){
+            numericObservations.sort((a, b) => a.value - b.value);
+            const count = numericObservations.length;
+            const middleIndex = Math.floor(count / 2);
+            if (count % 2 === 0) {
+              // Return average of two middle values
+              aggregatedValue = (parseFloat(numericObservations[middleIndex - 1].value) + parseFloat(numericObservations[middleIndex].value))/2;
+              aggregatedUnit = numericObservations[middleIndex - 1].unit === numericObservations[middleIndex].unit ? numericObservations[middleIndex].unit : "Mixed";
+            } else {
+              // Return value of the middle index
+              aggregatedValue = numericObservations[middleIndex].value;
+              aggregatedUnit = validateUnit(numericObservations[middleIndex].unit);
+            }
+          } else {
+            aggregatedValue = null;
+            aggregatedUnit = validateUnit(null);
+          }
+          
+          break;
+        }
         case 'COUNT': {
           aggregatedValue = observations.length;
           aggregatedUnit = validateUnit(null);

herald-core/herald-lexer.js

@@ -18,7 +18,7 @@ function getHeraldLexer(ignoreErrors = false) {
        conjunctionAnd: ['AND'],
        conjunctionOr: ['OR'],
        field: ['LABEL', 'VALUE', 'UNIT', 'START', 'END', 'NUMERIC'],
-       aggregation: ['AVERAGE', 'COUNT', 'SUM', 'MIN', 'MAX', 'MOST FREQUENT'],
+       aggregation: ['AVERAGE', 'MEDIAN', 'COUNT', 'SUM', 'MIN', 'MAX', 'MOST FREQUENT'],
        selection: ['FIRST', 'LAST', 'ANY'],
        relationship: ['RATIO BETWEEN', 'DIFFERENCE BETWEEN', 'EQUALITY OF'],
        existence: ['EXISTS', 'NOT EXISTS'],

herald-ui/herald-ui-binding.js

@@ -362,6 +362,7 @@ function abbreviateKeyword(keyword) {
     "MONTH": "M",
     "YEAR": "Y",
     "AVERAGE": "Avg",
+    "MEDIAN": "Med",
     "AND": "And",
     "OR": "Or",
     "LABEL": "Lbl",

herald-ui/herald-ui-editor.js

@@ -25,7 +25,7 @@
  */ 
 const queryTypeKeywords = {
   selection: ['FIRST', 'LAST', 'ANY'],
-  aggregation: ['AVERAGE', 'COUNT', 'SUM', 'MIN', 'MAX', 'MOST FREQUENT'],
+  aggregation: ['AVERAGE', 'MEDIAN', 'COUNT', 'SUM', 'MIN', 'MAX', 'MOST FREQUENT'],
   existence: ['EXISTS', 'NOT EXISTS'],
   relationship: ['RATIO BETWEEN', 'DIFFERENCE BETWEEN', 'EQUALITY OF'],
 };

herald-ui/herald-ui-generic.js

@@ -398,6 +398,7 @@ function initHeraldQueryEntryForm() {
                         <button class="dropdown-item herald-quick-add" data-action="EXISTS">EXISTS</button>
                         <button class="dropdown-item herald-quick-add" data-action="NOT EXISTS">NOT EXISTS</button>
                         <button class="dropdown-item herald-quick-add" data-action="AVERAGE">AVERAGE</button>
+						<button class="dropdown-item herald-quick-add" data-action="MEDIAN">MEDIAN</button>
                         <button class="dropdown-item herald-quick-add" data-action="COUNT">COUNT</button>
                         <button class="dropdown-item herald-quick-add" data-action="SUM">SUM</button>
                         <button class="dropdown-item herald-quick-add" data-action="MIN">MIN</button>