[英]Get Y value across .NET chart series from X value
.NET图表使用C#。
我正在尝试绘制几个波形图,并且希望在图表区域上移动鼠标,并让我的工具提示在此X值位置显示图表中每个系列的Y值。
| at xValue 12 | |
| _ = 3 | |
| * = 2 | * * |
| ________|______________________________*_____ |
| / | * |
| __________*/*********|***************************** |
| * | |
| * | |
|______________________|_____________________________________|
有点像上面这张图。 以下是我的代码的一个版本:
void chart1_MouseMove(object sender, MouseEventArgs e)
{
var pos = e.Location;
_point.X = e.Location.X;
_point.Y = e.Location.Y;
try
{
if ((chart1.ChartAreas[0].AxisX.PixelPositionToValue(e.X) >= 0) && (chart1.ChartAreas[0].AxisX.PixelPositionToValue(e.X) <= max))
{
//Crossair
chart1.ChartAreas[0].CursorX.SetCursorPixelPosition(_point, true);
//Tooltips
double xValue = chart1.ChartAreas[0].AxisX.PixelPositionToValue(e.X);
double yValue = chart1.ChartAreas[0].AxisY.PixelPositionToValue(e.Y);
string all_Data_Values = "";
foreach (var series in chart1.Series)
{
all_Data_Values = all_Data_Values + Environment.NewLine + series.Name + ": " + yValue;
}
tooltip.Show("At " + Math.Truncate(xValue * 1000) / 1000 + all_Data_Values, this.chart1, pos.X - 40, pos.Y - 20);
}
}
catch (Exception exception)
{
//
}
}
这就是我所拥有的,现在它仅显示鼠标光标位置的Y值。 我尝试了其他代码,试图以某种方式将x值映射到chart1.Series [],但它也不起作用。
(这是对代码请求的回应,该代码要求在给定像素坐标的情况下查找最接近的值。)
我的操作与您的操作有所不同,因为实际上是在用户移动鼠标时设置图表的“光标”,但是希望这会为您提供足够的信息,以使其适合您的需求...
这是我为客户端X坐标计算X轴坐标的方法:
private double calcCursorGraphX(int clientX)
{
var xAxis = _chart.ChartAreas[CHART_INDEX].AxisX;
int xRight = (int) xAxis.ValueToPixelPosition(xAxis.Maximum) - 1;
int xLeft = (int) xAxis.ValueToPixelPosition(xAxis.Minimum);
if (clientX > xRight)
{
return xAxis.Maximum;
}
else if (clientX < xLeft)
{
return xAxis.Minimum;
}
else
{
return xAxis.PixelPositionToValue(clientX);
}
}
给定从上述方法返回的X值,我们可以查找最接近的先前值:
private int nearestPreceedingValue(double x)
{
var bpData = _chart.Series[SERIES_INDEX].Points;
int bpIndex = bpData.BinarySearch(x, (xVal, point) => Math.Sign(x - point.XValue));
if (bpIndex < 0)
{
bpIndex = ~bpIndex; // BinarySearch() returns the index of the next element LARGER than the target.
bpIndex = Math.Max(0, bpIndex-1); // We want the value of the previous element, so we must decrement the returned index.
} // If this is before the start of the graph, use the first valid data point.
return bpIndex;
}
然后,您就有一个索引,可用于从_chart.Series[SERIES_INDEX].Points
查找值。
我不确定这是否适合您的数据在图表中存储的方式,但这就是我的方式。
[编辑]这是缺少的BinarySearch扩展方法。 将其添加到可访问的静态类中。 如果您不使用代码合同,则用自己的错误处理替换“合同”内容。
/// <summary>
/// Searches the entire sorted IList{T} for an element using the specified comparer
/// and returns the zero-based index of the element.
/// </summary>
/// <typeparam name="TItem">The type of the item.</typeparam>
/// <typeparam name="TSearch">The type of the searched item.</typeparam>
/// <param name="list">The list to be searched.</param>
/// <param name="value">The value to search for.</param>
/// <param name="comparer">The comparer that is used to compare the value with the list items.</param>
/// <returns>
/// The zero-based index of item in the sorted IList{T}, if item is found;
/// otherwise, a negative number that is the bitwise complement of the index of the next element that is larger than item,
/// or - if there is no larger element - the bitwise complement of Count.
/// </returns>
public static int BinarySearch<TItem, TSearch>(this IList<TItem> list, TSearch value, Func<TSearch, TItem, int> comparer)
{
Contract.Requires(list != null);
Contract.Requires(comparer != null);
int lower = 0;
int upper = list.Count - 1;
while (lower <= upper)
{
int middle = lower + (upper - lower) / 2;
int comparisonResult = comparer(value, list[middle]);
if (comparisonResult < 0)
{
upper = middle - 1;
}
else if (comparisonResult > 0)
{
lower = middle + 1;
}
else
{
return middle;
}
}
return ~lower;
}
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