Question

In ZedGraph, how do I draw a time (like 00:00, 02:00, 04:00, etc.) on the Y axis and date (like 12-Apr-11, 13-Apr-11, 14-Apr-11, etc.) on the X axis?
The bar settings has been set to BarType.Stack.

Sample code will be very helpful.

Answer 1

Here is a sample that I constructed. I was not sure what sort of data you would plot along the Y Axis using a time format except for something like an accrued amount of time (such as number of hours employees worked).

ZedGraph uses an XDate format for time along the axes, which are doubles converted from datetimes. However in a stacked bar, I am not sure if ZedGraph can aggregate the times properly (I couldn’t get it to work). Thus, in my example I used a Linear type for the Y Axis and changed the format so that it displays as hours and minutes.

Note that the min and max of both axes’ scales have been set. This is especially important along the X axis, as the auto setting gets it wrong. Some of the other settings I specify clean up the minor tic marks, etc.

Here’s an example showing a stacked bar graph for number of hours worked by three employees during each day:

const int NumberOfBars = 5;

GraphPane myPane = zedGraphControl1.GraphPane;
myPane.Title.Text = "Employee Hours";
myPane.BarSettings.Type = BarType.Stack;
myPane.BarSettings.ClusterScaleWidth = 1D;

// X AXIS SETTINGS
myPane.XAxis.Title.Text = "Date";
myPane.XAxis.Type = AxisType.Date;
myPane.XAxis.Scale.Format = "dd-MMM-yy";
myPane.XAxis.Scale.MajorUnit = DateUnit.Day;
myPane.XAxis.Scale.MajorStep = 1;
myPane.XAxis.Scale.Min = new XDate(DateTime.Now.AddDays(-NumberOfBars));
myPane.XAxis.Scale.Max = new XDate(DateTime.Now);
myPane.XAxis.MajorTic.IsBetweenLabels = true;
myPane.XAxis.MinorTic.Size = 0;
myPane.XAxis.MajorTic.IsInside = false;
myPane.XAxis.MajorTic.IsOutside = true;

// Y AXIS SETTINGS
myPane.YAxis.Title.Text = "Hours Worked";
myPane.YAxis.Type = AxisType.Linear;
myPane.YAxis.Scale.Format = @"00:\0\0";
myPane.YAxis.Scale.Min = 0;
myPane.YAxis.Scale.Max = 24;
myPane.YAxis.Scale.MajorStep = 1;
myPane.YAxis.MinorTic.Size = 0;

// Construct some sample data
Random r = new Random();
List<double> DatesX = new List<double>();
double[] JohnHours = new double[NumberOfBars];
double[] JoanHours = new double[NumberOfBars];
double[] JaneHours = new double[NumberOfBars];

for (int i = 0; i < NumberOfBars; i++)
{
    DatesX.Add(new XDate(DateTime.Today.AddDays(-i)));
    JohnHours[i] = r.Next(1, 9);
    JoanHours[i] = r.Next(1, 9);
    JaneHours[i] = r.Next(1, 9);
}
myPane.AddBar("John", DatesX.ToArray(), JohnHours, Color.Red);
myPane.AddBar("Joan", DatesX.ToArray(), JoanHours, Color.Blue);
myPane.AddBar("Jane", DatesX.ToArray(), JaneHours, Color.Green);