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12.6.1 Line and Scatter Graphs

       

Line and Scatter graphs are used to plot various types of X-Y data. In its simplest form, a line graph is nothing more than a set of data points on an X-Y grid, possibly connected by line segments.

Figure 12.8 illustrates a multi-data set line graph which shows a set of observed data values and a second set of data which shows a function fitted to this data. The raw data points are defined as Data Set 1 with Line Style/None connecting the points, producing an X-Y plot. The fitted curve is specified as Data Set 2 and has Marker/None and Line Style/Solid selected. All the scaling and tick marks were generated automatically.

On a color display, each line typically appears in a different color. You can also specify what type line connects the points (e.g. dotted, dashed, etc.). The New Graph Options... dialog on the Options menu of the main sheet controls how colors, line styles, and markers are initially defined for a new graph.

The data points to be graphed do not need to be spaced evenly on the X-axis. In fact, for scatter plots they do not even need to be in order. Line and spline segments will connect adjacent points in the value lists. A break in a line or spline segment is indicated by leaving an X-Y coordinate cell blank. This is usually done by inserting a blank line or column at the appropriate location.

The data for an X-axis or Y-axis can be either text or numeric. If the data are text, the text values become the labels for successive locations on the axis. A typical use is to show monthly values of some type in a trend.

If the cells in a range are formatted as dates or times, then the corresponding axis will be adjusted and displayed in appropriate units for the times and dates specified.

   figure4280
Figure 12.8: Line Graph of Observed Values and Fitted Curve

As is the case with all graphs, line plots can be saved as Encapsulated PostScript files. These files will print properly on either black and white or color printers.


next up previous contents index
Next: 12.6.2 Bar Graphs Up: 12.6 Types of Graphs Previous: 12.6 Types of Graphs

NExS User's Guide, Version 1.4.5
Grey Trout Software
11 April 1999