mathtool/lib/tools/chi_square.dart

// tools/chi_square.dart
import 'package:flutter/material.dart';
import 'package:rational/rational.dart';
import 'package:fl_chart/fl_chart.dart';
import '../utils/math_utils.dart';

class ChiSquarePage extends StatefulWidget {
  @override
  _ChiSquarePageState createState() => _ChiSquarePageState();
}

class _ChiSquarePageState extends State<ChiSquarePage> {
  final TextEditingController aController = TextEditingController();
  final TextEditingController bController = TextEditingController();
  final TextEditingController cController = TextEditingController();
  final TextEditingController dController = TextEditingController();

  String result = '';
  List<BarChartGroupData> barGroups = [];
  bool showChart = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('卡方检验')),
      body: Padding(
        padding: EdgeInsets.all(16),
        child: Column(
          children: [
            Text('请输入2×2列联表数据:'),
            SizedBox(height: 20),
            Row(
              children: [
                Expanded(child: _buildInputField('a', aController)),
                SizedBox(width: 10),
                Expanded(child: _buildInputField('b', bController)),
              ],
            ),
            Row(
              children: [
                Expanded(child: _buildInputField('c', cController)),
                SizedBox(width: 10),
                Expanded(child: _buildInputField('d', dController)),
              ],
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: _calculate,
              child: Text('计算卡方值'),
            ),
            SizedBox(height: 20),
            if (result.isNotEmpty)
              Card(
                child: Padding(
                  padding: EdgeInsets.all(16),
                  child: Text(
                    result,
                    style: TextStyle(fontSize: 16),
                  ),
                ),
              ),
            SizedBox(height: 20),
            if (showChart && barGroups.isNotEmpty)
              Expanded(
                child: Card(
                  elevation: 4,
                  child: Padding(
                    padding: EdgeInsets.all(16),
                    child: Column(
                      children: [
                        Text(
                          '等高堆积条形图',
                          style: TextStyle(
                            fontSize: 18,
                            fontWeight: FontWeight.bold,
                          ),
                        ),
                        SizedBox(height: 10),
                        Expanded(
                          child: BarChart(
                            BarChartData(
                              alignment: BarChartAlignment.spaceAround,
                              maxY: 1.0,
                              barTouchData: BarTouchData(
                                enabled: false,
                              ),
                              titlesData: FlTitlesData(
                                show: true,
                                bottomTitles: AxisTitles(
                                  sideTitles: SideTitles(
                                    showTitles: true,
                                    getTitlesWidget: (value, meta) {
                                      switch (value.toInt()) {
                                        case 0:
                                          return Text('组1');
                                        case 1:
                                          return Text('组2');
                                        default:
                                          return Text('');
                                      }
                                    },
                                  ),
                                ),
                                leftTitles: AxisTitles(
                                  sideTitles: SideTitles(
                                    showTitles: true,
                                    getTitlesWidget: (value, meta) {
                                      return Text('${(value * 100).toInt()}%');
                                    },
                                    reservedSize: 40,
                                  ),
                                ),
                                topTitles: AxisTitles(
                                  sideTitles: SideTitles(showTitles: false),
                                ),
                                rightTitles: AxisTitles(
                                  sideTitles: SideTitles(showTitles: false),
                                ),
                              ),
                              gridData: FlGridData(
                                show: true,
                                drawVerticalLine: false,
                                getDrawingHorizontalLine: (value) {
                                  return FlLine(
                                    color: Colors.grey.withOpacity(0.3),
                                    strokeWidth: 1,
                                  );
                                },
                              ),
                              borderData: FlBorderData(
                                show: false,
                              ),
                              barGroups: barGroups,
                            ),
                          ),
                        ),
                        SizedBox(height: 10),
                        Row(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: [
                            _buildLegend(Colors.blue, '类别A'),
                            SizedBox(width: 20),
                            _buildLegend(Colors.red, '类别B'),
                          ],
                        ),
                      ],
                    ),
                  ),
                ),
              ),
          ],
        ),
      ),
    );
  }

  Widget _buildInputField(String label, TextEditingController controller) {
    return TextField(
      controller: controller,
      keyboardType: TextInputType.numberWithOptions(signed: true, decimal: true),
      decoration: InputDecoration(
        labelText: label,
        border: OutlineInputBorder(),
      ),
    );
  }

  Widget _buildLegend(Color color, String text) {
    return Row(
      mainAxisSize: MainAxisSize.min,
      children: [
        Container(
          width: 16,
          height: 16,
          color: color,
        ),
        SizedBox(width: 8),
        Text(text),
      ],
    );
  }

  void _calculate() {
  try {
    final a = int.parse(aController.text);
    final b = int.parse(bController.text);
    final c = int.parse(cController.text);
    final d = int.parse(dController.text);

    final n = a + b + c + d;
    final numerator = Rational.fromInt(n) *
    Rational.fromInt((a * d - b * c) * (a * d - b * c));
    final denominator = Rational.fromInt((a + b) * (c + d) * (a + c) * (b + d));
    final K2 = numerator / denominator;

    // 计算比例用于图表
    final totalGroup1 = a + b;
    final totalGroup2 = c + d;
    
    final proportionA1 = totalGroup1 > 0 ? a / totalGroup1 : 0.0;
    final proportionB1 = totalGroup1 > 0 ? b / totalGroup1 : 0.0;
    final proportionA2 = totalGroup2 > 0 ? c / totalGroup2 : 0.0;
    final proportionB2 = totalGroup2 > 0 ? d / totalGroup2 : 0.0;

    // 创建条形图数据 - 修复堆积问题
    barGroups = [
      BarChartGroupData(
        x: 0,
        groupVertically: true, // 启用垂直堆积
        barsSpace: 4, // 条形之间的间距
        barRods: [
          BarChartRodData(
            fromY: 0,
            toY: proportionA1,
            color: Colors.blue,
            width: 30,
          ),
          BarChartRodData(
            fromY: proportionA1, // 从第一个条形的顶部开始
            toY: proportionA1 + proportionB1,
            color: Colors.red,
            width: 30,
          ),
        ],
      ),
      BarChartGroupData(
        x: 1,
        groupVertically: true, // 启用垂直堆积
        barsSpace: 4, // 条形之间的间距
        barRods: [
          BarChartRodData(
            fromY: 0,
            toY: proportionA2,
            color: Colors.blue,
            width: 30,
          ),
          BarChartRodData(
            fromY: proportionA2, // 从第一个条形的顶部开始
            toY: proportionA2 + proportionB2,
            color: Colors.red,
            width: 30,
          ),
        ],
      ),
    ];

    setState(() {
      result = 'K² = ${MathUtils.rationalToString(K2)}\n'
      '近似值: ${K2.toDouble().toStringAsFixed(4)}';
      showChart = true;
    });
  } catch (e) {
    setState(() {
      result = '错误: $e';
      showChart = false;
    });
  }
}

  @override
  void dispose() {
    aController.dispose();
    bController.dispose();
    cController.dispose();
    dController.dispose();
    super.dispose();
  }
}