The Pie Chart plug-in for HEC-DSSVue allows you to plot a pie chart of any value of interest (e.g., flow, stage, or reservoir storage) for a single date and time at multiple locations. Either a two-dimensional (2D) or three-dimensional (3D) plot can be created. The pie chart is plotted using a default color sequence, but you can change the color of each individual slice. The transparency of the chart can also be adjusted. By default, all sections are labeled with the site name, units, and percentage of the total. The unit and percent labels can be individually turned off, or section labels can be turned off altogether. A legend is created below the chart by default, which can also be turned off. The section labels and legend are updated dynamically. The final product can be printed, or it can be saved to a graphics file to be included in presentations, documents, or web pages.

Creating a Pie Chart

First, load a data set into DSSVue. Select the data type to plot by clicking the drop-down list to select the C part of the DSS path. Select the time interval using the drop-down list for the D part of the path. Specific sites and dates/times can be selected by Ctrl-clicking on each row of the table, or all of the data can be used to create the plot by pressing Ctrl-A.

An example of creating a pie chart of reservoir storage data is shown below.  Use the Display menu, and then point to Charts, click Pie Charts to open the main pie chart window. A window with a chart panel will appear, as shown below. Click the desired options, as described below.  If you need to change the selection of data to be plotted, or otherwise do not wish to create a pie chart, the window can be closed using either the Cancel button at the bottom of this window, or from the File menu, click Close from the pie chart window. 

Date/Time

Select the date and time from the Date/Time drop-down list at the top-left of the main chart window. If only one date/time was selected from the data set before opening this window, only one date will appear in this list. Otherwise, all dates will be present, with the earliest date selected by default. 

Chart Dimension

A two-dimensional (2D) or three-dimensional (3D) chart can be created by selecting 2D or 3D in the Dimension option box to the left of the plot panel. An example of a 2D plot is shown in below.

Sort Type

The Sort Type options to the left of the plot panel allow you to specify whether the data should be sorted by site name, by data value, or by the order the data is listed in the DSS file ("unsorted"). Click By Name to sort the plot alphabetically, starting with the first site name at the top of the plot. This option allows quick identification of particular sites, particularly if a large number of sites were included.
Select By Value to sort the data by ascending or descending data values. This option creates neat and visually appealing plots that can be used to compare sites and quickly identify important differences between sites.
Select Unsorted to plot the data in the order in which it appears in the DSS file. This option respects the order of the DSS file but usually will not produce charts that are as clear or useful as those created using the By Name or By Value options.

Sort Order

The Sort Order options at the left of the plot window allow you to specify whether to sort the data in ascending or descending order. The Ascending option sorts the data around the chart clockwise, with the first value plotted at the top of the chart. Descending reverses the sort order by plotting the data in increasing order counter-clockwise around the plot. If Unsorted is selected for Sort Type, the Sort Order option will be disabled.

Transparency

The transparency of the entire pie chart can be changed to enhance the clarity or visual appeal of the plot. Drag the slider in the Transparency option box to the left to decrease the transparency and drag to the right to increase transparency. The transparency is dynamically updated as the slider is dragged. To turn transparency off and create an opaque plot, drag the slider to the far left. 

Section Colors

The color of each individual slice in the pie chart can be altered by clicking the Change Section Colors button. A color selection window will appear (below). Select the site name from the drop-down list to the right of the window, and then click on a color. The color of the selected slice is dynamically updated on the pie chart. Drag the color chooser window to one side to view the changes in the main chart window. 

Printing and Saving

To print the pie chart, from the File menu, click Print of the pie chart window.

To save the pie chart to a graphics file, choose File → Save As from the pie chart menu. The chart can be saved as either a JPEG or PNG file. Select the desired extension in the Files of type field, and then type a name in the File name field, or browse for an existing file to replace with the current one. Then click Save. The selected extension will be appended to the file name automatically.