Question

我有以下对象数组。我需要获取具有最高import React, { Component } from 'react'; import ReactDOM from "react-dom"; import Pagination from "react-js-pagination"; import { BrowserRouter as Router, Route, IndexRoute, Link, } from 'react-router-dom'; import ProjectDetails from './ProjectDetails'; import DashboardContainer from '../UIcomponent/DashboardContainer'; const pannelWidth = { width: '90%' }; const pannelHeader = { color: 'white' }; const pannelFooter = { float: 'right' }; class ProjectList extends Component { constructor(props) { super(props); this.state = { activePage: 1, searchText: '', isdiagram:true, isMax:false, projectList: [], originalProjectList: [] }; //this.handlePageChange = this.handlePageChange.bind(this); this.projectDetails = this.projectDetails.bind(this); this.deleteMessage = this.deleteMessage.bind(this); this.updateInputValue = this.updateInputValue.bind(this); this.setSize=this.setSize.bind(this); } componentDidMount() { let d = ''; $.get("http://localhost:8008/api/navigation/all", function (data) { d = data; this.setState({ projectList: d, originalProjectList: d }); }.bind(this)); } handlePageChange(pageNumber) { this.setState({ activePage: pageNumber }); console.log(this.state.projectList); } projectDetails(item, index) { console.log(index); } deleteMessage(item, index) { showconfrim("Do you want to delete this Project?", this.deleteProject(item, index)); console.log('delete'); } deleteProject(item, index) { $("#confirmwindow").modal('hide'); console.log('delete'); } setSize(){ this.setState({ isMax:!this.state.isMax }); if(!this.state.isMax){ //clear style for jquery animate; $(this.refs.selfdiv).attr("style",null); setTimeout(()=>{ $(this.refs.selfdiv).animate({ top:'0px', right: '0px', bottom: '0px', left: '0px' },500); },100); } console.log(this.props.children); if(this.props.children[1].props['data-event']){ var self=this; setTimeout(()=>{ self.props.children[1].props['data-event'].call(); },700); } } updateInputValue(event) { this.setState({ searchText: event.target.value }, function () { let textToSearch = this.state.searchText; let originalData = this.state.projectList; if (textToSearch != undefined || textToSearch != '') { let searchData = []; for (var i = 0; i < this.state.projectList.length; i++) { if (this.state.projectList[i].name.indexOf(textToSearch) != -1 || this.state.projectList[i].description.indexOf(textToSearch) != -1) { searchData.push(this.state.projectList[i]); } } this.setState({ projectList: searchData }); } if(textToSearch == '') { this.setState({ projectList: this.state.originalProjectList, }); } }); } render() { var listItems = this.state.projectList.map((item, index) => { return <tr key={index}> <td onClick={e => this.projectDetails(item, index)}><a><u>{item.name}</u></a></td> <td>{item.description}</td> <td><i className="glyphicon glyphicon-trash" onClick={e => this.deleteMessage(item, index)}></i></td> </tr> }); return ( <div className="container" style={pannelWidth} ref="selfdiv"> <br /> <div className="panel panel-primary"> <div className="panel-heading"> <div className="row"> <div className="col-md-2 col-lg-2"> <h4 style={pannelHeader}>Project List</h4> </div> <div className="col-md-6 col-lg-6"> <input type="text" className="form-control" placeholder="Search" value={this.state.searchText} onChange={this.updateInputValue}/> </div> <div className="col-md-2 col-lg-2"> <button className="btn btn-sm btn-success">Create New Project</button> </div> <div className="col-md-2 col-lg-2"> <div className="captiontoolbar buttoncontainer"> <span onClick={this.setSize} style={pannelFooter} className={ this.state.isMax ? ("boxMaxsize glyphicon glyphicon-resize-small") : ("boxMaxsize glyphicon glyphicon-fullscreen") }></span> </div> </div> </div> </div> <div className="panel-body"> <table className="table table-striped"> <thead> <tr> <th><b>Project Name</b></th> <th><b>Description</b></th> <th><b>Action</b></th> </tr> </thead> <tbody> {listItems} </tbody> </table> </div> <div style={pannelFooter}> <Pagination activePage={this.state.activePage} itemsCountPerPage={3} totalItemsCount={this.state.projectList.length} pageRangeDisplayed={5} onChange={this.handlePageChange.bind(this)} /> </div> </div> </div> ); } } export default ProjectList;的项目的属性。我有一个只返回MoveCount的函数。但我想获得MoveCount和Latitude的价值。

我使用的功能如下：

Longitude

物件：

var res = Math.max.apply(Math,movers.map(function(o){
return o.MoveCount, o.Latitude, o.Longitude;}))

alert('Max y = ' + res);

Answer 1

您可以使用基于MoveCount的自定义排序功能。这将保留整个对象。

var movers = [
  {
    "MoveCount":3,
    "DepartureCountryCode":"MG",
    "Latitude":-18.766947,
    "Longitude":46.869107
  },
  {
    "MoveCount":2,
    "DepartureCountryCode":"MU",
    "Latitude":-20.348404,
    "Longitude":57.552152
  },
  {
    "MoveCount":4,
    "DepartureCountryCode":"ZA",
    "Latitude":-30.559482,
    "Longitude":22.937506
  }
];

movers.sort(function(a,b){ return b.MoveCount - a.MoveCount; });
var highestMoveCount = movers[0]; // get the item with the highest MoveCount
console.log(highestMoveCount);

上面的代码返回一个按MoveCount降序排序的数组。

Answer 2

对数组进行排序，使用map函数更改输出的对象并从排序的数组中获取第一项。

＆＃13;

var movers = [
{
   "MoveCount": 3,
   "DepartureCountryCode": "MG",
   "Latitude": -18.766947,
   "Longitude": 46.869107
},
{   
   "MoveCount": 2,
   "DepartureCountryCode": "MU",
   "Latitude": -20.348404,
   "Longitude": 57.552152
},
{
   "MoveCount": 4,
   "DepartureCountryCode": "ZA",
   "Latitude": -30.559482,
   "Longitude": 22.937506
}];

const highest = movers.sort((a,b) => b.MoveCount - a.MoveCount)
                      .map(({MoveCount, Latitude, Longitude}) => ({MoveCount, Latitude, Longitude}))[0];

console.log(highest);

＆＃13;

Answer 3

你可以减少推动者总是选择更大的推动者：

appender.rolling.policies.size.type = SizeBasedTriggeringPolicy
appender.rolling.policies.size.size = 2 MB

appender.rolling.strategy.type = DefaultRolloverStrategy
appender.rolling.strategy.action.type = Delete
appender.rolling.strategy.action.basePath = ${sys:es.logs.base_path}${sys:file.separator}
appender.rolling.strategy.action.maxDepth = 1
appender.rolling.strategy.action.ifLastModified.type = IfLastModified
appender.rolling.strategy.action.ifLastModified.age = 3d

Answer 4

你可以像别人说的那样排序，但这会带来O（nlogn）的复杂性。或者您可以只比较O（n）复杂度中的最高值。

const movers = [{"MoveCount":3,"DepartureCountryCode":"MG","Latitude":-18.766947,"Longitude":46.869107},
{"MoveCount":2,"DepartureCountryCode":"MU","Latitude":-20.348404,"Longitude":57.552152},
{"MoveCount":4,"DepartureCountryCode":"ZA","Latitude":-30.559482,"Longitude":22.937506}]

let highest = movers[0]

for (let index=1; index<movers.length; index += 1) {
  let movObj = movers[index];
  if (movObj.MoveCount > highest.MoveCount) {
    highest = movObj;
  }
}

console.log(highest)
// if you only want certain fields

const certainFieldsRes = ({MoveCount, Latitude, Longitude}) => ({
 MoveCount, Latitude, Longitude
})
console.log(certainFieldsRes(highest))

Answer 5

我可能会使用Array.prototype.reduce来遍历数组，以找到MoveCount最高的项目。

let movers = [
  {
    "MoveCount":3,
    "DepartureCountryCode":"MG",
    "Latitude":-18.766947,
    "Longitude":46.869107
  },
  {
    "MoveCount":2,
    "DepartureCountryCode":"MU",
    "Latitude":-20.348404,
    "Longitude":57.552152
  },
  {
    "MoveCount":4,
    "DepartureCountryCode":"ZA",
    "Latitude":-30.559482,
    "Longitude":22.937506
  }
];

let getHighestMoveCount = function (arr) {
  let o = arr.reduce(function (accumulator, currentValue, currentIndex) {
    // if this is the first item, we have nothing to compare against,
    // just return this item
    if (currentIndex === 0) {
      return currentValue;
    } else {
      // if this item has a higher MoveCount than the current highest,
      // return it
      if (currentValue.MoveCount > accumulator.MoveCount) {
        return currentValue;
      } else {
        // otherwise return the current highest
        return accumulator;
      }
    }
  });
  // return the object that has the highest MoveCount
  return o;
  // This returns the entire object, if you wanted a new object with
  // only the MoveCount Latitude and Longitude, you would do
  // this instead:
  // return {MoveCount: o.MoveCount, Latitude: o.Latitude, Longitude: o.Longitude};
};

console.log(getHighestMoveCount(movers));

如何从json对象中的max value属性获取对象属性

5 个答案: