Enhancing Plots (5)

Creating Plots

Enhancing Plots

Specifying Connecting Lines

To specify whether or not to connect plotted points, you use the INTERPOL= (or I=) option in the SYMBOL statement. Connecting lines can be straight lines, smoothed lines, or vertical lines drawn from plotted points to a horizontal line at zero or the minimum value on the Y axis.

Possible values include NONE, JOIN, NEEDLE, SPLINE, HILO, STD, and more.

Examples

INTERPOL=NONE specifies unconnected data points.

     symbol1 value=triangle interpol=none;

Display plot with I=NONE.

INTERPOL=JOIN specifies data points connected with straight lines.

     symbol1 value=triangle interpol=join;

Display plot with I=JOIN.

INTERPOL=NEEDLE specifies that a vertical line is drawn from each point on the plot to a horizontal line at zero on the Y axis unless, as in this case, zero does not appear on the Y axis.

     symbol1 value=triangle interpol=needle;

Display plot with I=NEEDLE.

INTERPOL=SPLINE connects the points with a smoothed line.
```
symbol1 value=triangle interpol=spline;
```

Display plot with I=SPLINE.

If you specify the INTERPOL= option and VALUE=NONE, you get an interpolated line with no plotting symbol.

     symbol1 value=none interpol=spline;

Display plot with I=SPLINE and no plotting symbol.

If the interpolation goes beyond the minimum or maximum values, that part of the interpolation will not be shown on the graph (see the second and third graphs above for examples). To correct this problem, you can expand the axis range using the HAXIS= and VAXIS= options.