The Spline Chart is similar to the line chart except that it connects data points by using splines rather than straight lines. The chart is used as an alternative to the line chart, but more specifically for representing data that requires the use of curve fittings.

You need to set the ChartType property to Spline either from the Properties window or in code behind to create the Spline Chart.

You can set the Stacking property to Stacked or Stacked100pc to create the stacking Spline Chart.

Consider that you are the sales analyst of a company ABC that releases its annual sales report every year. Being the sales analyst, you are asked to compare the sales of last two years, thereby creating a sales comparison report. The report needs to show the increasing/decreasing trends of the sales in the two years based upon the given sales data.

You can use the Spline Chart to create the required sales comparison report.

Sample Data Table

Month	Sales in 2014 (1000 $)	Sales in 2015 (1000 $)
Jan	8	23
Feb	11	24
Mar	12	22
Apr	15	22
May	17	24
Jun	18	27
Jul	19	26
Aug	20	27
Sep	22	24
Oct	22	26
Nov	23	27
Dec	20	25

Important Points

Spline Chart

The above chart shows comparison between ABC sales for 2014 and 2015.

Number of series: two (2014 and 2015)
Number of Y values per point: one

Here is the code demonstrating the implementation:

Visual Basic
C#

Visual Basic

' create a datatable
Dim dt As New DataTable("Sales - 2014 vs 2015")

' add columns to the datatable
dt.Columns.Add("Month", GetType(String))
dt.Columns.Add("Sales in 2014", GetType(Integer))
dt.Columns.Add("Sales in 2015", GetType(Integer))

' add rows to the datatable
dt.Rows.Add("Jan", 8, 23)
dt.Rows.Add("Feb", 11, 24)
dt.Rows.Add("Mar", 12, 22)
dt.Rows.Add("Apr", 15, 22)
dt.Rows.Add("May", 17, 24)
dt.Rows.Add("Jun", 18, 27)
dt.Rows.Add("Jul", 19, 26)
dt.Rows.Add("Aug", 20, 27)
dt.Rows.Add("Sep", 22, 24)
dt.Rows.Add("Oct", 22, 26)
dt.Rows.Add("Nov", 23, 27)
dt.Rows.Add("Dec", 20, 25)

' clear data series collection
FlexChart1.Series.Clear()

' create data series
Dim series1 As New C1.Win.Chart.Series()
Dim series2 As New C1.Win.Chart.Series()

                  
' add the data series to the data series collection
FlexChart1.Series.Add(series1)
FlexChart1.Series.Add(series2)

' name the series
series1.Name = "2014"
series2.Name = "2015"

' specify the datasource for the chart
FlexChart1.DataSource = dt

' bind X-axis and Y-axis
FlexChart1.BindingX = "Month"
series1.Binding = "Sales in 2014"
series2.Binding = "Sales in 2015"

' set the chart type to spline
FlexChart1.ChartType = C1.Chart.ChartType.Spline

// create a datatable
DataTable dt = new DataTable("Sales - 2014 vs 2015");

// add columns to the datatable
dt.Columns.Add("Month", typeof(string));
dt.Columns.Add("Sales in 2014", typeof(int));
dt.Columns.Add("Sales in 2015", typeof(int));

// add rows to the datatable
dt.Rows.Add("Jan", 8, 23);
dt.Rows.Add("Feb", 11, 24);
dt.Rows.Add("Mar", 12, 22);
dt.Rows.Add("Apr", 15, 22);
dt.Rows.Add("May", 17, 24);
dt.Rows.Add("Jun", 18, 27);
dt.Rows.Add("Jul", 19, 26);
dt.Rows.Add("Aug", 20, 27);
dt.Rows.Add("Sep", 22, 24);
dt.Rows.Add("Oct", 22, 26);
dt.Rows.Add("Nov", 23, 27);
dt.Rows.Add("Dec", 20, 25);

// clear data series collection
flexChart1.Series.Clear();

// create data series
C1.Win.Chart.Series series1 = new C1.Win.Chart.Series();
C1.Win.Chart.Series series2 = new C1.Win.Chart.Series();
            
// add the data series to the data series collection
flexChart1.Series.Add(series1);
flexChart1.Series.Add(series2);

// name the series
series1.Name = "2014";
series2.Name = "2015";

// specify the datasource for the chart
flexChart1.DataSource = dt;

// bind X-axis and Y-axis
flexChart1.BindingX = "Month";
series1.Binding = "Sales in 2014";
series2.Binding = "Sales in 2015";

// set the chart type to spline
flexChart1.ChartType = C1.Chart.ChartType.Spline;

Month	Sales in 2014 (1000 $)	Sales in 2015 (1000 $)
Jan	8	23
Feb	11	24
Mar	12	22
Apr	15	22
May	17	24
Jun	18	27
Jul	19	26
Aug	20	27
Sep	22	24
Oct	22	26
Nov	23	27
Dec	20	25

Month	Sales in 2014 (1000 $)	Sales in 2015 (1000 $)
Jan	8	23
Feb	11	24
Mar	12	22
Apr	15	22
May	17	24
Jun	18	27
Jul	19	26
Aug	20	27
Sep	22	24
Oct	22	26
Nov	23	27
Dec	20	25

Month	Sales in 2014 (1000 $)	Sales in 2015 (1000 $)
Jan	8	23
Feb	11	24
Mar	12	22
Apr	15	22
May	17	24
Jun	18	27
Jul	19	26
Aug	20	27
Sep	22	24
Oct	22	26
Nov	23	27
Dec	20	25