calculate_records.dart

import 'dart:convert';

import 'package:http/http.dart' as http;

void main() async {
  final data = await getData();

  // get the record list of any keys, 'Score' as an example
  final recordList = (data['Information'] as List)
          .firstWhere((t) => (t as Map).keys.first == 'Score')['Score']
      ['RecordList'];

  print(recordList);

  // get the average of the records
  final average = recordList
          .map((record) => double.tryParse("${record['Value']}") ?? 0)
          .reduce((a, b) => a + b) /
      recordList.length;

  print(average);
}

Future<Map> getData() async {
  final res = await http.get(Uri.parse(
      "https://hkbu-api.hibluesky.co:8443/Iaq/Information/1100/2023-07-02T16:00:00.000Z/2023-07-03T07:00:00.00Z/3600000"));

  return jsonDecode(res.body) as Map;
}