我在两个不同的数据网格中有两个数据，我想从行中获取值，以便我依靠欧氏距离公式。我可以获取第二个 datagridview 中的值，但无法获取第一个 datagridview 中的数据。我试图写 foreach，但我仍然在那里foreach (DataGridViewRow row1 in dataGridView1.Rows){ foreach (DataGridViewRow row in dataGridView2.Rows) { double NilaiPixelGrid1 = Convert.ToDouble(row1.Cells[2].Value.ToString()); double NilaiRedGrid1 = Convert.ToDouble(row1.Cells[3].Value.ToString()); double NilaiGreenGrid1 = Convert.ToDouble(row1.Cells[4].Value.ToString()); double NilaiBlueGrid1 = Convert.ToDouble(row1.Cells[5].Value.ToString()); double NilaiPixel = Convert.ToDouble(row.Cells[2].Value.ToString()); double NilaiRed = Convert.ToDouble(row.Cells[3].Value.ToString()); double NilaiGreen = Convert.ToDouble(row.Cells[4].Value.ToString()); double NilaiBlue = Convert.ToDouble(row.Cells[5].Value.ToString()); double dist = Math.Pow((NilaiPixelGrid1 - NilaiPixel), 2) + Math.Pow((NilaiRedGrid1 - NilaiRed), 2) + Math.Pow((NilaiGreenGrid1 - NilaiGreen), 2) + Math.Pow((NilaiBlueGrid1 - NilaiBlue), 2); }}System.NullReferenceException：“未将对象引用设置为对象的实例。”
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凤凰求蛊
TA贡献1825条经验 获得超4个赞
安全运行以避免null异常
public double ConvertToDouble(Object obj) {
double convertedValue = 0;
if(obj == null) return convertedValue ;
Double.TryParse(obj.ToString(), out convertedValue);
return convertedValue;
}
foreach (DataGridViewRow outerRow in dataGridView1.Rows) {
String distValue = "";
double NilaiPixelGrid1 = ConvertToDouble(outerRow.Cells[2].Value);
double NilaiRedGrid1 = ConvertToDouble(outerRow.Cells[3].Value);
double NilaiGreenGrid1 = ConvertToDouble(outerRow.Cells[4].Value);
double NilaiBlueGrid1 = ConvertToDouble(outerRow.Cells[5].Value);
//inner loop
foreach (DataGridViewRow innerRow in dataGridView2.Rows) {
double NilaiPixel = ConvertToDouble(innerRow.Cells[2].Value);
double NilaiRed = ConvertToDouble(innerRow.Cells[3].Value);
double NilaiGreen = ConvertToDouble(innerRow.Cells[4].Value);
double NilaiBlue = ConvertToDouble(innerRow.Cells[5].Value);
double dist = Math.Pow((NilaiPixelGrid1 - NilaiPixel), 2) +
Math.Pow((NilaiRedGrid1 - NilaiRed), 2) +
Math.Pow((NilaiGreenGrid1 - NilaiGreen), 2) +
Math.Pow((NilaiBlueGrid1 - NilaiBlue), 2);
//use dist value
distValue += " " + dist;
}
Console.WriteLine(distValue);
}
回首忆惘然
TA贡献1847条经验 获得超11个赞
如果您没有注意到，那么行计数从 0 开始，而不是从 1 开始。
如何计算欧氏距离的示例
public static double EuclideanDistance(Tuple<double, double> first, Tuple<double, double> second)
{
var difItem1 = first.Item1 - second.Item1;
var difItem2 = first.Item2 - second.Item2;
return Math.Sqrt(difItem1 * difItem1 + difItem2 * difItem2);
}
如果您有更多维度，那么您可以创建过载。
public static double EuclideanDistance(Tuple<double, double, double, double> first, Tuple<double, double, double, double> second)
{
var difItem1 = first.Item1 - second.Item1;
var difItem2 = first.Item2 - second.Item2;
var difItem3 = first.Item3 - second.Item3;
var difItem4 = first.Item4 - second.Item4;
return Math.Sqrt(difItem1 * difItem1 + difItem2 * difItem2 + difItem3 * difItem3 + difItem4 * difItem4);
}
所以我可以创建一个数据集：
DataTable table1 = new DataTable("From");
table1.Columns.Add("a", typeof(double));
table1.Columns.Add("r", typeof(double));
table1.Columns.Add("g", typeof(double));
table1.Columns.Add("b", typeof(double));
table1.Rows.Add(255, 23, 234, 55);
table1.Rows.Add(255, 26, 234, 55);
DataTable table2 = new DataTable("To");
table2.Columns.Add("a", typeof(double));
table2.Columns.Add("r", typeof(double));
table2.Columns.Add("g", typeof(double));
table2.Columns.Add("b", typeof(double));
table2.Rows.Add(255, 23, 231, 7);
table2.Rows.Add(255, 27, 231, 7);
DataSet set = new DataSet("Distance");
set.Tables.Add(table1);
set.Tables.Add(table2);
然后循环这些值并计算距离并将其打印出来
var results = new List<double>();
for (int i = 0; i < Math.Min(set.Tables["From"].Rows.Count, set.Tables["To"].Rows.Count); i++)
{
var from = Tuple.Create(
(double)set.Tables["From"].Rows[i]["a"], (double)set.Tables["From"].Rows[i]["r"],
(double)set.Tables["From"].Rows[i]["g"], (double)set.Tables["From"].Rows[i]["b"]);
var to = Tuple.Create(
(double)set.Tables["To"].Rows[i]["a"], (double)set.Tables["To"].Rows[i]["r"],
(double)set.Tables["To"].Rows[i]["g"], (double)set.Tables["To"].Rows[i]["b"]);
results.Add(EuclideanDistance(from, to));
}
Console.WriteLine("Results are: " + string.Join(", ", results));
在你的情况下，你还可以设置
DataGridView1.DataSource = set;
DataGridView1.DataMember = "From";
DataGridView2.DataSource = set;
DataGridView2.DataMember = "To";
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