小组统计

Question

我想通过以下分组制作DataGrid

我的问题是如何在群组标题中执行“平均值”？

下面是一个巨大的xaml

    <DataGrid x:Name="dataGrid" Grid.Column="1" CanUserResizeRows="False" CanUserSortColumns="False" GridLinesVisibility="None" AutoGenerateColumns="False" ItemsSource="{Binding List}" HeadersVisibility="Column" Grid.IsSharedSizeScope="True">
        <DataGrid.Columns>
            <DataGridTextColumn Binding="{Binding A}" Header="A"/>
            <DataGridTextColumn Binding="{Binding B}" Header="B"/>
            <DataGridTextColumn Binding="{Binding C}" Header="C"/>
            <DataGridTextColumn Binding="{Binding Group}" Header="Group"/>
        </DataGrid.Columns>
        <DataGrid.GroupStyle>
            <GroupStyle>
                <GroupStyle.ContainerStyle>
                    <Style TargetType="GroupItem">
                        <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="GroupItem">
                                    <Border BorderBrush="Gray" BorderThickness="0.5" CornerRadius="4" Margin="3">
                                        <Border.Background>
                                            <LinearGradientBrush EndPoint="1,0.5" StartPoint="0,0.5">
                                                <GradientStop Color="#FFACACAC" Offset="0"/>
                                                <GradientStop Color="White" Offset="1"/>
                                            </LinearGradientBrush>
                                        </Border.Background>
                                        <StackPanel>
                                            <Grid>
                                                <Grid.ColumnDefinitions>
                                                    <ColumnDefinition SharedSizeGroup="A"/>
                                                    <ColumnDefinition SharedSizeGroup="B"/>
                                                    <ColumnDefinition/>
                                                </Grid.ColumnDefinitions>
                                                <TextBlock Text="{Binding Name}" Margin="10,0,10,0"/>
                                                <TextBlock Grid.Column="1" Text="{Binding ItemCount}" Margin="10,0,0,0"/>
                                                <TextBlock Grid.Column="2" Text="test" Margin="10,0,0,0"/>
                                            </Grid>
                                            <Expander>
                                                <Border BorderBrush="Gray" BorderThickness="0.5" Margin="3">
                                                    <ItemsPresenter/>
                                                </Border>
                                            </Expander>
                                        </StackPanel>
                                    </Border>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>
                    </Style>
                </GroupStyle.ContainerStyle>
            </GroupStyle>
        </DataGrid.GroupStyle>
    </DataGrid>

产生此输出

我可以输出组名（绿色箭头）和计数器（红色箭头）。

如何输出任一列的平均值（让它为A）而不是“test”？

Answer 1

您需要使用转换器将Items属性转换为平均值。像这样：

public class ItemsToAverageConverter : IValueConverter {
  public object Convert(object value, Type targetType, object parameter,
                                                       CultureInfo culture){
    var propName = Convert.ToString(parameter);
    var items = (IEnumerable<Item>) value;
    var prop = typeof(Item).GetProperty(propName);
    if(prop == null) return Binding.DoNothing;
    return items.Average(i => (double) prop.GetValue(i));
  }
  public object Convert(object value, Type targetType, object parameter,
                                                       CultureInfo culture){
    throw new NotImplementedException();
  }
}

我认为项目类型为Item。您在XAML代码中使用该转换器，可能需要一些StringFormat来格式化值表示。

假设您在某处可访问此资源：

<local:ItemsToAverageConverter x:Key="avgConverter"/>

代码应该像这样改变：

<TextBlock Grid.Column="1" Text="{Binding Items,
                                  Converter={StaticResource avgConverter},
                                  ConverterParameter=A,
                                  StringFormat=f2}" Margin="10,0,0,0"/>