I have a list of players consist of 5 objects..

"data": [
    {
      "id": 74,
      "name": "name 1",
      "type": "defender",
      "value": 10
    },
    {
      "id": 7422,
      "name": "name 2",
      "type": "defender",
      "value": 20
    },
    {
      "id": 2213,
      "name": "Max",
      "type": "defender",
      "value": 30
    },
    {
      "id": 3333,
      "name": "John",
      "type": "defender",
      "value": 40
    },
    {
      "id": 8793,
      "name": "Alex",
      "type": "defender",
      "value": 50
    }
  ]

How can I get a list consist of 3 items of the highest values from data list ?

expected results => [Max , John , Alex]

I need only the top 3 items based on highest value

CodePudding user response：

First sort data based on value then find out the max value

void main() {
  List<Map<String, dynamic>> data = [
    {"id": 74, "name": "name 1", "type": "defender", "value": 10},
    {"id": 7422, "name": "name 2", "type": "defender", "value": 20},
    {"id": 2213, "name": "Max", "type": "defender", "value": 30},
    {"id": 3333, "name": "John", "type": "defender", "value": 40},
    {"id": 8793, "name": "Alex", "type": "defender", "value": 50}
  ];



// sort the data based on 
  if (data != null && data.isNotEmpty) {
    data.sort((a, b) => a['value'].compareTo(b['value']));
  }
// you can simply do this
  for( int i =data.length-3; i< data.length;i  ){
    print(data[i]["name"]);
  }
  

  // truncate the max value from the bottom part
  List<Map<String, dynamic>> data1 = data.sublist(data.length-3, data.length);
  
// show the data whom hold the max value
  data1.reversed.forEach((e){
    print(e["name"]);
  });
}

Output: Alex John Max

N.B: you used reversed if you want to print from high to low after getting sorted value

CodePudding user response：

        List<Map<String, dynamic>> users =[
    {
      "id": 74,
      "name": "name 1",
      "type": "defender",
      "value": 10
    },
    {
      "id": 7422,
      "name": "name 2",
      "type": "defender",
      "value": 20
    },
    {
      "id": 2213,
      "name": "Max",
      "type": "defender",
      "value": 30
    },
    {
      "id": 3333,
      "name": "John",
      "type": "defender",
      "value": 40
    },
    {
      "id": 8793,
      "name": "Alex",
      "type": "defender",
      "value": 50
    }
  ]


      if (users != null && users.isNotEmpty) {
      users.sort((a, b) => a['value'].compareTo(b['value']));
      print(users.last['value']);

users list already sorted in above code. so last 3 items of the list are max value!

CodePudding user response：

For me if you have a standard that the value is higher in 20 or 30

List<Map<String,dynamic>> items = [{
      "id": 74,
      "name": "name 1",
      "type": "defender",
      "value": 10
    },
    {
      "id": 7422,
      "name": "name 2",
      "type": "defender",
      "value": 20
    },
    {
      "id": 2213,
      "name": "Max",
      "type": "defender",
      "value": 30
    },
    {
      "id": 3333,
      "name": "John",
      "type": "defender",
      "value": 40
    },
    {
      "id": 8793,
      "name": "Alex",
      "type": "defender",
      "value": 50
    }];

then for sorting them is like this with where

items.where((e) => e['value'] > 20).toList()..sort((a,b)=>b['value'].toString().compareTo(a['value'].toString()));

and you will get a set of another data

[
{id: 8793, name: Alex, type: defender, value: 50}, 
{id: 3333, name: John, type: defender, value: 40}, 
{id: 2213, name: Max, type: defender, value: 30}
]

CodePudding user response：

why dont you sort this list by values and then take first three value from list.