Plotting Module - Graph Settings
There are twelve options on the Graph menu shown below; Axis Ranges, Axis Labels, Edit Legend, Draw Points, Draw Point Frequency, Draw Legend, Draw Grid, 1:1 Aspect Ratio, Zoom Operations, Add New Series, Remove Series and Export to Excel. The only graph operation that does not involve the use of a menu command is zooming in on a region within a graph; this is done by clicking and dragging with the mouse to select the region.
When graphs are displayed on screen, a graph indicator is displayed on the legend of each graph. This indicator identifies which graph is currently selected; it is bright green on the currently selected graph and dark red on all others, as shown below.
This indicator is not output when printing or copying from the Plotting module. Most of the commands on the Graph menu affect only the currently selected graph.
The first command is Axis Ranges, which displays the Axes – Ranges dialog shown below.
As you can see, it is divided into two halves, one with controls for the X axis and the other with the same controls for the Y axis. Each half has three sections: Title, Range and Increments. The axis title is displayed in the Title section. Please note that you cannot change the titles using this dialog; you use the Axis Labels command to do this. In the Range section, you can set the minimum and maximum values of the axis. The Scale property is used to modify the numeric values displayed – all values are multiplied by the scale you input. In the Increments section, you can specify the increments at which values are marked along each axis. Using the drop-down list, you can opt to specify either the increment value or the number of increments. In addition, you can specify the number of tick marks between each major increment on the axis.
If you press the Defaults button at the bottom of the dialog, the Plotting module calculates reasonable default values for the ranges and increments, based on the extents of the graph.
As discussed earlier, the Plotting module displays structure snapshots by default with a 1:1 aspect ratio between the X and Y axes. To maintain this aspect ratio, the ranges that you specify in the Axes – Ranges dialog are adjusted, so that the difference between the maximum and minimum is always the same on both axes. The 1:1 Aspect Ratio option allows you to override this, if required.
This command displays the Axes – Labels dialog shown below. This dialog has four inputs, namely Title and Units for each axis. The Title and Units inputs are combined to form the axis label for each of the two axes.
A legend is displayed above each graph in the Plotting module, showing the name of each data set in the graph and its associated line colour and symbol. The Edit Legend command allows the text in the legend to be changed. It displays a dialog box similar to the one shown below, with an entry for each data set. Simply select the name of a data set to edit it. The line colour and symbol for the selected data set is displayed beside the edit box.
This option toggles the display of data points on or off. Shown below is a graph with the Draw Points option enabled and the same graph with it disabled. Please note that this option affects all graphs, not just the currently selected one.
This option displays the Draw Point Frequency Dialog, shown below. This option allows you to decide the frequency of the data points, when the Show Data Points option is switched on.
Draw Point Frequency
The default setting is Draw Every Point. If the Draw Fewer Points option is enabled, you must enter an integer value, n. The number of data points drawn will be automatically adjusted to 1/n of all the data points, that is, only every nth data point will be displayed. In some cases, where the program cannot determine the graph’s independent axis itself, you must also use the Independent Variable drop-down list, to identify the appropriate axis. This input is necessary for the algorithm to draw evenly spaced data points to operate correctly. The diagram below shows the same plot with all data points drawn and with every fifth data point drawn.
Draw Point Frequency Example
The option toggles the legend on or off.
This option toggles the display of grid lines on or off. When this option is enabled, grid lines are drawn at every tick mark along each axis. Shown below is a graph with the Grid option enabled and the same graph with the option disabled. Please note that this option affects all graphs, not just the currently selected one.
This feature allows the user to switch on/off the automatic sizing and re-sizing of the structure snapshot plots, as previously discussed.
The Plotting module allows you to zoom in on a region within a graph and to zoom to the graph extents. When you change the zoom area, it stores the previous zoom area and allows you to return to it subsequently. These operations are described below. Please note that when you change the zoom area on a plot, the Plotting module will prompt you to save the changes if you switch to a different page or exit the application.
The cursor is used to zoom in on a region within a graph. Simply press the left mouse button within the graph and drag the mouse to select a region that you wish to zoom in on. Shown below is graph before and after zooming in on a region. The tick mark increment is automatically changed when you zoom in or out.
After zooming in on a region, you can use the Zoom All menu command to adjust the zoom area so that it encloses the whole graph. Finally, the Zoom Previous menu command allows you to return to the previous zoom area.
This feature allows you to both add horizontal or vertical indicator lines to the graph and/or to add entire additional series of points to the graph. The dialog shown below appears when you click on the Add New Series option.
Each series added to the plot is given an initial default title, which can be changed if required. The title will appear in the plot legend, beside a representation of the line or series of points added. The type of series to be added to the plot is specified via the Type drop-down list shown below.
The Horizontal and Vertical options allow the specification of a straight line. When the Horizontal option is selected, the Value specified corresponds to the Y-axis point at which the horizontal line is drawn. When the Vertical option is selected, the Value specified corresponds to the X-axis point at which the vertical line is drawn.
The Define Direct and From File options allow the specification of a Multipoint series. When the Define Direct option is selected, the Data button opens the dialog shown in the figure below.
Simply enter the set of X,Y points which define your data series and press OK to confirm. This option is particularly suitable for entering series with a modest number of points.
The From File option can be used to import a set of data points from a text file and is more suitable for large numbers of points. The values should be comma-delimited with one X, Y pair per line. The Data button opens the dialog shown below when the From File option is selected.
Simply type the full path name to the text file into the menu and press OK to confirm.
Shown below is a plot with horizontal and vertical lines and an arbitrary series of points all added.
Plot with Several Added Series
This feature allows you to remove any series from the plot. A dialog similar to that shown below appears when the Remove Series option is selected from the Graph menu; it provides a list of all data series in the current plot.
A series can be removed from a plot by selecting it from the list and pressing OK. Multiple series can be selected and removed from the plot, if required.
This feature allows you to export all plot data to Microsoft Excel. The data is formatted in Excel as one or more pairs of columns each containing a set of X,Y pairs describing one series from the graph.