JavaScript ArcGIS StatisticDefinition.onStatisticField用法及代码示例

基本信息

以下是所在类或对象的基本信息。

AMD: require(["esri/rest/support/StatisticDefinition"], (StatisticDefinition) => { /* code goes here */ });

ESM: import StatisticDefinition from "@arcgis/core/rest/support/StatisticDefinition";

类： esri/rest/support/StatisticDefinition

继承: StatisticDefinition > Accessor

自从：用于 JavaScript 4.0 的 ArcGIS API

用法说明

StatisticDefinition.onStatisticField函数(或属性)的定义如下：

onStatisticField String

定义将为其计算统计数据的字段。这可以是服务字段名称或 SQL 表达式。有关示例，请参见下面的片段。

例子：

// query for the sum of the population in all features
let sumPopulation = {
  onStatisticField: "POP_2015",  // service field for 2015 population
  outStatisticFieldName: "Pop_2015_sum",
  statisticType: "sum"
}
let query = layer.createQuery();
query.outStatistics = [ sumPopulation ];
layer.queryFeatures(query)
  .then(function(response){
     let stats = response.features[0].attributes;
     console.log("output stats:", stats);
  });

// query for the average of the population change for all features
// Notice that you can pass a SQL expression as a field name to calculate statistics
let populationChangeDefinition = {
  onStatisticField: "POP_2015 - POP_2010",  // service field for 2015 population
  outStatisticFieldName: "avg_pop_change_2015_2010",
  statisticType: "avg"
}
let query = layer.createQuery();
query.outStatistics = [ populationChangeDefinition ];
layer.queryFeatures(query)
  .then(function(response){
     let stats = response.features[0].attributes;
     console.log("Average change:", stats.avg_pop_change_2015_2010);
  });

// query for the average of the population change grouped by regions
// query result will also return an extent for each group encompassing
// all features in each group.
let populationChangeDefinition = {
  onStatisticField: "POP_2015 - POP_2010",  // service field for 2015 population
  outStatisticFieldName: "avg_pop_change_2015_2010",
  statisticType: "avg"
};
let aggregatedExtent = {
  statisticType: "envelope-aggregate"
};
let query = layer.createQuery();
query.groupByFieldsForStatistics = ["Region"];
query.outStatistics = [ populationChangeDefinition, aggregatedExtent ];
layer.queryFeatures(query).then(displayResults);

相关用法

注：本文由纯净天空筛选整理自arcgis.com大神的英文原创作品 StatisticDefinition.onStatisticField。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。