Add top N and bottom N filter functions, closes #241.

docs/sources/reference/functions.md

@@ -78,6 +78,38 @@ max(interval)
 ```
 **Deprecated**, use `aggregateBy(interval, max)` instead.
 
+
+Filter
+---------
+
+### top
+
+```
+top(N, value)
+```
+
+Returns top N series, sorted by _value_, which can be one of: _avg_, _min_, _max_, _median_.
+
+Examples:
+```
+top(10, avg)
+top(5, max)
+```
+
+### bottom
+
+```
+bottom(N, value)
+```
+
+Returns bottom N series, sorted by _value_, which can be one of: _avg_, _min_, _max_, _median_.
+
+Examples:
+```
+bottom(5, avg)
+```
+
+
 ## Trends
 
 ### trendValue

src/datasource-zabbix/DataProcessor.js

@@ -116,6 +116,22 @@ export default class DataProcessor {
     return sortByTime(new_timeseries);
   }
 
+  static limit(order, n, orderByFunc, timeseries) {
+    let orderByCallback = DataProcessor.aggregationFunctions[orderByFunc];
+    let sortByIteratee = (ts) => {
+      let values = _.map(ts.datapoints, (point) => {
+        return point[0];
+      });
+      return orderByCallback(values);
+    };
+    let sortedTimeseries = _.sortBy(timeseries, sortByIteratee);
+    if (order === 'bottom') {
+      return sortedTimeseries.slice(0, n);
+    } else {
+      return sortedTimeseries.slice(-n);
+    }
+  }
+
   static AVERAGE(values) {
     var sum = 0;
     _.each(values, function(value) {
@@ -198,6 +214,8 @@ export default class DataProcessor {
       max: _.partial(this.aggregateWrapper, this.MAX),
       median: _.partial(this.aggregateWrapper, this.MEDIAN),
       sumSeries: this.sumSeries,
+      top: _.partial(this.limit, 'top'),
+      bottom: _.partial(this.limit, 'bottom'),
       setAlias: this.setAlias,
     };
   }

src/datasource-zabbix/datasource.js

@@ -92,7 +92,11 @@ export class ZabbixAPIDatasource {
 
         _.forEach(target.functions, func => {
           func.params = _.map(func.params, param => {
+            if (typeof param === 'number') {
+              return +this.templateSrv.replace(param.toString(), options.scopedVars);
+            } else {
               return this.templateSrv.replace(param, options.scopedVars);
+            }
           });
         });
 
@@ -181,6 +185,7 @@ export class ZabbixAPIDatasource {
         return getHistory.then(timeseries_data => {
           let transformFunctions   = bindFunctionDefs(target.functions, 'Transform');
           let aggregationFunctions = bindFunctionDefs(target.functions, 'Aggregate');
+          let filterFunctions      = bindFunctionDefs(target.functions, 'Filter');
           let aliasFunctions       = bindFunctionDefs(target.functions, 'Alias');
 
           // Apply transformation functions
@@ -189,6 +194,11 @@ export class ZabbixAPIDatasource {
             return timeseries;
           });
 
+          // Apply filter functions
+          if (filterFunctions.length) {
+            timeseries_data = sequence(filterFunctions)(timeseries_data);
+          }
+
           // Apply aggregations
           if (aggregationFunctions.length) {
             let dp = _.map(timeseries_data, 'datapoints');

src/datasource-zabbix/metricFunctions.js

@@ -5,6 +5,7 @@ var index = [];
 var categories = {
   Transform: [],
   Aggregate: [],
+  Filter: [],
   Trends: [],
   Alias: []
 };
@@ -99,6 +100,26 @@ addFuncDef({
   defaultParams: ['1m', 'avg'],
 });
 
+addFuncDef({
+  name: 'top',
+  category: 'Filter',
+  params: [
+    { name: 'number', type: 'int' },
+    { name: 'value', type: 'string', options: ['avg', 'min', 'max', 'median'] }
+  ],
+  defaultParams: [5, 'avg'],
+});
+
+addFuncDef({
+  name: 'bottom',
+  category: 'Filter',
+  params: [
+    { name: 'number', type: 'int' },
+    { name: 'value', type: 'string', options: ['avg', 'min', 'max', 'median'] }
+  ],
+  defaultParams: [5, 'avg'],
+});
+
 addFuncDef({
   name: 'trendValue',
   category: 'Trends',