为一周中的每一天创建一个带有单独线条的折线图？

Question

我在数据库表中有以下数据， 列：日期、小时（从 1 到 24）和温度。

我想创建一个折线图，在 x 轴上显示从 1 到 24 的小时数，在 Y 轴上显示温度。

现在棘手的部分是我想为每个日期设置不同的颜色线。因此，如果日期是 2012-01-15，那么我有一条从 1 到 24 的红线，显示温度的变化。如果日期是 2012-01-14，那么蓝色也是从 1 到 24。

明确地说，我想在一张图表中包含多个日期。

这是我的一些代码

        SqlConnection conn2 = new SqlConnection(@"connectionString");
        conn2.Open();

        SqlCommand cmd2 = new SqlCommand();
        cmd2.Connection = conn2;
        cmd2.CommandText = "SELECT * FROM observation WHERE day BETWEEN @fromDate AND @toDate ORDER BY day ASC, hour ASC ";
        cmd2.Parameters.AddWithValue("fromDate", dateTimePicker2.Value.Date);
        cmd2.Parameters.AddWithValue("toDate", dateTimePicker3.Value.Date);



        SqlDataReader reader = cmd2.ExecuteReader();
        DataSet ds = new DataSet();
        DataTable dt = new DataTable("dateRange");
        dt.Columns.Add("day");
        dt.Columns.Add("hour");
        dt.Columns.Add("temp");

        DataRow dr = dt.NewRow();
        int counter = 0;

        while (reader.Read())
        {
            if (reader[1].ToString() != dt.TableName)
            {
                if (dt.Rows.Count != 0 && dt.TableName != "dateRange")
                {
                    dt.AcceptChanges();
                    ds.Tables.Add(dt);
                    counter++;
                }
                dt = new DataTable(reader[1].ToString());
                dt.Columns.Add("day"):                    
                dt.Columns.Add("hour");
                dt.Columns.Add("temp");

            }
            dr = dt.NewRow();
            dr[0] = reader[2];
            dr[1] = reader[3];
            dt.Rows.Add(dr);
        }
        if (dt.Rows.Count != 0)
        {
            dt.AcceptChanges();
            ds.Tables.Add(dt);
        }
        else
        {
            lblError.Visible = false;
        }

        for (int i = 0; i < counter; i++)
        {
            chart1.Series[i].Name = i.ToString();
            chart1.Series[i].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Line;
            chart1.Series[i].BorderWidth = 5;
            if (i % 2 == 0)
            {
                chart1.Series[i].Color = Color.Red;
            }
            else
            {
                chart1.Series[i].Color = Color.Green;
            }

            chart1.DataSource = ds.Tables[i];
            chart1.Series[i].XValueMember = "hour";
            chart1.Series[i].YValueMembers = "temp";
        }

        chart1.Legends[0].Alignment = StringAlignment.Center;
        chart1.Legends[0].Docking = System.Windows.Forms.DataVisualization.Charting.Docking.Top;

        chart1.DataBind();
        chart1.Visible = true;

        cmd2.Connection.Close();

谢谢！

Answer 1

为了创建多条线，您必须创建多个系列，但我不确定您在这里使用的图表类型是关于图表的非常好的教程

http://www.4guysfromrolla.com/articles/072209-1.aspx

Chart1.Series[0].Points.FindMinByValue().Color = Color.Red; 这应该会改变每个点的颜色。

Answer 2

我找到的一个解决方案是重新格式化我的数据源。我创建了一个 DataTable，第一列是 Hours，它从 1 到 24。以下列是我想要表示的每一天。

有两个查询。第一个是知道间隔中有多少天，并创建适当数量的列和系列。第二个查询是引入所有数据的查询。

代码如下：

        SqlConnection conn = new SqlConnection(connectionString);

        SqlCommand cmd = new SqlCommand();
        cmd.Connection = conn;
        cmd.CommandText = "SELECT day FROM observation WHERE day BETWEEN @from AND @to GROUP BY day";
        cmd.Parameters.AddWithValue("from", Convert.ToDateTime(dateFrom));
        cmd.Parameters.AddWithValue("to", Convert.ToDateTime(dateTo));
        cmd.Connection.Open();

        SqlDataReader rdr = cmd.ExecuteReader();

        DataTable dt = new DataTable("DATA");
        dt.Columns.Add("Hour");

        int days = 0;
        chart1.DataSource = dt;
        while (rdr.Read())
        {
            dt.Columns.Add(((DateTime)rdr[0]).ToString("yyyy-MM-dd"));

            if (days == 0)
            {
                chart1.Series[days].Name = ((DateTime)rdr[0]).ToString("yyyy-MM-dd");
            }
            else
            {
                chart1.Series.Add(((DateTime)rdr[0]).ToString("yyyy-MM-dd"));
            }
            chart1.Series[((DateTime)rdr[0]).ToString("yyyy-MM-dd")].XValueMember = "Hour";
            chart1.Series[((DateTime)rdr[0]).ToString("yyyy-MM-dd")].YValueMembers = ((DateTime)rdr[0]).ToString("yyyy-MM-dd");
            chart1.Series[((DateTime)rdr[0]).ToString("yyyy-MM-dd")].ChartType = System.Windows.Forms.DataVisualization.Charting.SeriesChartType.Line;
            days++;
        }
        rdr.Close();

        DataRow dr = dt.NewRow();
        for (int i = 1; i < 25; i++)
        {
            dr = dt.NewRow();
            dr["Hour"] = i;
            dt.Rows.Add(dr);
        }

        cmd.CommandText = "SELECT * FROM observation WHERE day BETWEEN @from2 AND @to2 ORDER BY day ASC, hour ASC ";
        cmd.Parameters.AddWithValue("from2", Convert.ToDateTime(fromDate));
        cmd.Parameters.AddWithValue("to2", Convert.ToDateTime(toDate));

        rdr = cmd.ExecuteReader();
        while (rdr.Read())
        {
            dt.Rows[((int)(rdr[2]) - 1)][(((DateTime)rdr[1]).ToString("yyyy-MM-dd"))] = rdr[3];   
        }

        cmd.Connection.Close();
        rdr.Close();

        dataGridView1.DataSource = dt;

        chart1.DataBind();
        chart1.Visible = true;

Answer 3

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

dtTest.Columns.Add("TimePoint", GetType(Integer))
dtTest.Columns.Add("Speed", GetType(Integer))

dtTest.Rows.Add(0, 0)
dtTest.Rows.Add(1000, 50)
dtTest.Rows.Add(2000, 50)
dtTest.Rows.Add(3000, 0)

With Chart1.ChartAreas(0)
  .AxisX.Minimum = 0
  .AxisX.Maximum = 3000
  .AxisY.Minimum = 0
  .AxisY.Maximum = 60
  .AxisY.Interval = 10
  .AxisX.Title = "Elapsed Time (ms)"
  .AxisY.Title = "Speed (km/hr)"
End With
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    With Chart1.Series(0)
      .Points.DataBind(dtTest.DefaultView, "TimePoint", "Speed", Nothing)
      .ChartType = DataVisualization.Charting.SeriesChartType.Line
      .BorderWidth = 4
    End With
End Sub