gps_history 0.0.4

Represents histories of GPS points. Handles millions of points quickly and using relatively little memory. Can import Google location history JSON files.

GPS History for Dart

Module intended to represent histories of GPS points. Features:

• Two types of GPS point: a lean one with just the bare minimums and one with more meta information such as heading, speed, etc. that's useful for GPX files for example.
• Different in-memory storage systems for GPS points: either simply list-based, or efficient binary representation of just 14 or 22 bytes per point (at the cost of small loss of accuracy that's below what GPS sensors provide anyway).
• Extremely low-memory and fast parser for Google location history JSON export. As a reference, a straighforward parser using the Dart JSON library on a ~500 MB history file takes about 2 GB of memory and on an Intel Core i7-8565U can produce about 140k points/s, while the custom parser takes almost no memory on top of the base memory use of the application and outputs points about 2.5x-3.5x faster. Parse Google location history on mobile devices without any worries about running out of RAM.
• Modular and extensible architecture: add your own points definitions, containers or persistence mechanisms.
• Many unit tests, examples and lots of documentation.
• Null safety.
• No dependencies on third party libraries.

Example

Reading a JSON file containing location history exported from Google:

import 'dart:io';
import 'package:gps_history/gps_history.dart';
import 'package:gps_history/gps_history_convert.dart';

void main() async {
  final filename = 'data/g_history_sample.json';

  final file = File(filename);
  final gpsPoints = GpcCompactGpsPoint();

  var fileStream = file.openRead();

  var points = fileStream.transform(GoogleJsonHistoryDecoder(
      minSecondsBetweenDatapoints: 240, accuracyThreshold: 500));

  await for (var p in points) {
    gpsPoints.add(p);
  }

  print('Read ${gpsPoints.length} points');

  // Calculate with what frequency the points have been recorded.
  var intervals = <int>[];
  GpsPoint? prevPoint;

  for (var p in gpsPoints) {
    if (prevPoint != null) {
      final diff = p.time.difference(prevPoint.time).inSeconds;
      intervals.add(diff);
    }
    prevPoint = p;
  }

  intervals.sort();

  if (intervals.isNotEmpty) {
    print('Median interval = ${intervals[intervals.length ~/ 2]} s');
  }
}