plotSetTextInterpreter

Purpose

Controls the text interpreter settings for a graph.

Format

plotSetTextInterpreter(&myPlot, interpreter[, location])
Parameters:
  • &myPlot (struct pointer) – A plotControl structure pointer.
  • interpreter (string) – "html", "plain", "latex".
  • location (string) – Optional argument, which attributes the interpreter change applies to : “all”, “legend”, “title” or “axes”. Default is “all”.

Examples

Plain interpreter

The HTML text interpreter treats certain characters, such as greater-than and less-than signs, as mark-up rather than literal text to display. The Plain text interpretor will allow you to use these symbols directly in your plot text labels.

new;

// Declare plotControl structure
struct plotControl myPlot;

// Initialize plotControl structure
myPlot = plotGetDefaults("hist");

// Set the interpreter of axes
plotSetTextInterpreter(&myPlot, "plain", "axes");

// Set the X-axis label, using the > character which would
// would fail with the default HTML interpreter.
plotSetXLabel(&myPlot, "Weight > 50 Kg");

// Create data
x = rndn(1e5, 1);

// Plot a histogram of the x data spread over 50 bins
plotHist(myPlot, x, 50);

HTML interpreter

You may add Greek letters, mathematical symbols, subscript and superscript to your title, axes and legend using HTML. To add HTML to a label, you can use plotSetTextInterpreter() to set “html” for the text to be interpreted as HTML.

// Set the interpreter of axes
plotSetTextInterpreter(&myPlot, "html", "axes");

label_string = "β";

// Set the X-axis label
plotSetXLabel(&myPlot, label_string);

The code above will add the letter \(\beta\) to the graph title. The HTML ‘sup’ tag will create superscript and the ‘sub’ tag will create subscript. For example:

label_string = "&sigma;<sup>2</sup>";

// Set the X-axis label
plotSetXLabel(&myPlot, label_string);

will add \(\sigma^2\) to your title. While,

label_string = "Y<sub>t-1</sub>";

// Set the X-axis label
plotSetXLabel(&myPlot, label_string);

will create \(Y_{t-1}\).

LaTeX Interpreter

You can also use LaTeX to add complex math expression, or non-Latin scripts to your title, axes, and legend. You can use plotSetTextInterpreter() to set “latex”for the text to be interpreted as LaTeX.

new;

// Declare plotControl structure
// and fill with default XY settings
struct plotControl myPlot;
myPlot = plotGetDefaults("xy");

// Set LaTeX text interpreter for all text on plot
plotSetTextInterpreter(&myPlot, "latex", "all");

font_name = "Times New Roman";

// Set up X-axis label
plotSetXLabel(&myPlot, "x", font_name, 20);

// Set LaTeX legend string
string legend_string = {
"y_1 = \\cos{(x - 1.5)}",
"y_2 = \\sin{(\\frac{x}{2})} = \\pm \\sqrt{\\frac{1-\\cos{(x)}}{2}}",
"y_3 = \\cos{(\\frac{x}{2})} = \\pm \\sqrt{\\frac{1+\\cos{(x)}}{2}}"};

plotSetLegend(&myPlot, legend_string, "bottom left inside", 1);
plotSetLegendBkd(&myPlot, 0);
plotSetLegendFont(&myPlot, font_name, 12);

// Set up title
title_string = "\\text{Trigonometric Functions}";
plotSetTitle(&myPlot, title_string, font_name, 18);

// Create data
n = 50;
x = seqa(0,(2*pi)/(n-1), n);

// Specify size of plot canvas
plotCanvasSize("px", 600 | 300);

// Draw plot
plotXY(myPlot, x, cos(x-1.5)~sin(x/2)~cos(x/2));

The plot is

_images/plotsettextinterpreter.jpg

Remarks

When the text interpreter is set to use LaTeX:

  • Since backslashes inside of a string represent the escaping of a character, use double backslashes to represent a backslash.

  • The default mode is that of an in-line equation. To add a section of strictly text, wrap the text only section in \\text{}. For example:

    "\\text{The formula is } \\alpha + \\beta_1 X + \\epsilon"
    
  • Text outside of a \\text{} section will use the TeX font. Text inside of a \\text{} section will use whatever font was specified for the label.

The plain text interpreter will allow you to pass in characters that would be invalid HTML, such as the symbols ‘<’ and ‘>’.

This function sets an attribute in a plotControl structure. It does not affect an existing graph, or a new graph drawn using the default settings that are accessible from the Tools > Preferences > Graphics menu. See GAUSS Graphics, for more information on the methods available for customizing your graphs.