Flutter移动平均线计算插件moving_average的使用

MovingAverage

moving_average 是一个用于计算移动平均值的库。它支持多种类型的移动平均算法，包括简单移动平均（Simple Moving Average）、加权移动平均（Weighted Moving Average）和指数移动平均（Exponential Moving Average）。下面将详细介绍如何使用这个插件。

Usage

安装

首先，在 pubspec.yaml 文件中添加依赖：

dependencies:
  moving_average: ^latest_version

然后运行 flutter pub get 来安装依赖。

示例代码

以下是一个完整的示例代码，展示了如何使用 moving_average 插件来计算不同类型的移动平均值。

import 'package:moving_average/moving_average.dart';

void main() {
  // 示例数据
  final values = [1, 2, 3, 4, 5];
  print("Values = $values");

  // 简单移动平均 (Simple Moving Average)
  final simpleMovingAverage = MovingAverage<num>(
    averageType: AverageType.simple,
    windowSize: 3,
    partialStart: true,
    getValue: (num n) => n,
    add: (List<num> data, num value) => value,
  );
  final movingAverage3 = simpleMovingAverage(values);
  print("Simple Moving Average, size 3, partial = $movingAverage3");

  // 加权移动平均 (Weighted Moving Average)
  final weightedMovingAverage = MovingAverage<num>(
    averageType: AverageType.weighted,
    windowSize: 3,
    getValue: (num n) => n,
    add: (List<num> data, num value) => value,
  );
  final weightedAverage3 = weightedMovingAverage(values);
  print("Weighted Moving Average, size 3 = $weightedAverage3");

  // 指数移动平均 (Exponential Moving Average)
  final exponentialMovingAverage = MovingAverage<num>(
    averageType: AverageType.exponential,
    factor: 0.1,
    getValue: (num n) => n,
    add: (List<num> data, num value) => value,
  );
  final exponentialAverage = exponentialMovingAverage(values);
  print("Exponential Moving Average, factor 0.1 = $exponentialAverage");

  // 对象类型的数据 (例如 Point 类)
  class Point {
    final double x;
    final double y;

    Point(this.x, this.y);

    @override
    String toString() => "Point(x: $x, y: $y)";
  }

  final points = [
    Point(1, 1),
    Point(2, 2),
    Point(3, 3),
    Point(4, 4),
    Point(5, 5),
  ];
  print("Points = $points");

  // 简单移动平均 (对象类型)
  final sma2 = MovingAverage<Point>(
    averageType: AverageType.simple,
    windowSize: 2,
    getValue: (p) => p.y,
    add: (data, value) => Point(data.last.x, value as double),
  );
  final movingAverage2 = sma2(points);
  print("Simple Moving Average, size 2 = $movingAverage2");

  // 加权移动平均 (对象类型)
  final wma2 = MovingAverage<Point>(
    averageType: AverageType.weighted,
    windowSize: 2,
    getValue: (p) => p.y,
    add: (data, value) => Point(data.last.x, value as double),
  );
  final weightedAverage2 = wma2(points);
  print("Weighted Moving Average, size 2 = $weightedAverage2");

  // 指数移动平均 (对象类型)
  final ema = MovingAverage<Point>(
    averageType: AverageType.exponential,
    factor: 0.1,
    getValue: (p) => p.y,
    add: (data, value) => Point(data.last.x, value as double),
  );
  final exponential = ema(points);
  print("Exponential Moving Average, factor 0.1 = $exponential");
}

参数说明

• averageType: 移动平均的类型，可以是 AverageType.simple、AverageType.weighted 或 AverageType.exponential。
• windowSize: 窗口大小，即参与计算的元素数量。
• partialStart: 是否允许部分窗口计算，默认为 false。如果设置为 true，则在窗口未填满时也会计算平均值。
• getValue: 从每个元素中提取数值的函数。
• add: 将新值添加到结果中的函数。

输出示例

运行上述代码后，输出如下：

Values = [1, 2, 3, 4, 5]
Simple Moving Average, size 3, partial = [1.0, 1.5, 2.0, 3.0, 4.0]
Weighted Moving Average, size 3 = [2.3333333333333335, 3.3333333333333335, 4.333333333333333]
Exponential Moving Average, factor 0.1 = [1.0, 1.9, 2.71, 3.439, 4.0951]
Points = [Point(x: 1.0, y: 1.0), Point(x: 2.0, y: 2.0), Point(x: 3.0, y: 3.0), Point(x: 4.0, y: 4.0), Point(x: 5.0, y: 5.0)]
Simple Moving Average, size 2 = [Point(x: 2.0, y: 1.5), Point(x: 3.0, y: 2.5), Point(x: 4.0, y: 3.5), Point(x: 5.0, y: 4.5)]
Weighted Moving Average, size 2 = [Point(x: 2.0, y: 1.6666666666666667), Point(x: 3.0, y: 2.6666666666666665), Point(x: 4.0, y: 3.6666666666666665), Point(x: 5.0, y: 4.666666666666666)]
Exponential Moving Average, factor 0.1 = [Point(x: 1.0, y: 1.0), Point(x: 2.0, y: 1.9), Point(x: 3.0, y: 2.71), Point(x: 4.0, y: 3.439), Point(x: 5.0, y: 4.0951)]

Features and Bugs

如果您有任何功能请求或发现任何问题，请在 issue tracker 上提交。

希望这个详细的示例能帮助您更好地理解和使用 moving_average 插件！