2.2 Plotting text strings

In many situations we need to annotate plots or maps with text strings; in GMT this is done using pstext. Apart from the common switches, there are 7 options that are particularly useful (Table 2.4).

Table 2.4: Some of the most frequently used options in pstext.

Option	Purpose
-Cdx/dy	Spacing between text and the text box (see -W)
-Ddx/dy	Offsets the projected location of the strings
-Gfill	Sets the color of the text
-L	Lists the font ids and exits
-N	Deactivates clipping at the borders
-Spen	Selects outline font and sets pen attributes
-W[fill][o[pen]]	Paint the text box; draw the outline if o is appended (also see -C)

**Figure 2.1:** Relationship between the text box and the extra clearance.
$\begin{figure}\centering\epsfig{figure=eps/GMT_pstext_clearance.eps}\end{figure}$

The size argument is the font size in points, the angle is the angle (measured counterclockwise) between the text's baseline and the horizontal, justify indicates which point on the text-string should correspond to the given x, y location, and text is the text string or sentence to plot. Figure 2.2 illustrates these concepts and shows the relevant two-character codes used for justification.

**Figure 2.2:** Justification (and corresponding character codes) for text strings.
$\begin{figure}\centering\epsfig{figure=eps/GMT_pstext_justify.eps}\end{figure}$

The text string can be one or several words and may include octal codes for special characters and escape-sequences used to select subscripts or symbol fonts. The escape sequences that are recognized by GMT are given in Table 2.5.

Table 2.5: GMT text escape sequences.

Code	Effect
@~	Turns symbol font on or off
@%fontno%	Switches to another font; @%% resets to previous font
@+	Turns superscript on or off
@-	Turns subscript on or off
@#	Turns small caps on or off
@!	Creates one composite character of the next two characters
@@	Prints the @ sign itself
@E @e	Æ æ
@O @o	Ø ø
@A @a	Å å

Note that these escape sequences (as well as octal codes) can be used anywhere in GMT including in arguments to the -B option. A chart of octal codes can be found in Appendix F in the GMT technical reference book. For accented European characters you must set CHAR_ENCODING to ISOLatin1 in your .gmtdefaults4 file.

Here we have used the ``here document'' notation in UNIX: The

EOF will treat the following lines as the input file until it detects the word EOF. We pipe the PostScript directly through ghostview (the - tells ghostview that piping is happening).