gnuplot documentation

70 SET-SHOW gnuplot 4.3 107
Justification of the plot titles within the key is controlled by Left or Right (default). The text and
sample can be reversed (reverse) and a box can be drawn around the key (box {...}) in a specified
linetype and linewidth, or a user-defined linestyle.
By default the first plot label is at the top of the key and successive labels are entered below it. The
invert option causes the first label to be placed at the bottom of the key, with successive labels entered
above it. This option is useful to force the vertical ordering of labels in the key to match the order of
box types in a stacked histogram.
The is a number of character heights to be added to or subtracted from the height
of the key box. This is useful mainly when you are putting a box around the key and want larger borders
around the key entries.
All plotted curves of plots and splots are titled according to the default option autotitles. The
automatic generation of titles can be suppressed by noautotitles; then only those titles explicitly
defined by (s)plot ... title ... will be drawn.
The set key autotitle columnheader command causes the first entry in each column of input data
to be interpreted as a text string and used as a title for the corresponding plot. If the quantity being
plotted is a function of data from several columns, gnuplot may be confused as to which column to draw
the title from. In this case it is necessary to specify the column explicitly in the plot command, e.g.
plot "datafile" using (($2+$3)/$4) title 3 with lines.
An overall title can be put on the key (title "") — see also syntax (p. 38) for the distinction
between text in single- or double-quotes. The key title uses the same justification as do the plot titles.
The defaults for set key are on, right, top, vertical, Right, noreverse, noinvert, samplen 4,
spacing 1.25, title "", and nobox. The default is the same as that used for the plot
borders. Entering set key default returns the key to its default configuration.
The key is drawn as a sequence of lines, with one plot described on each line. On the right-hand side
(or the left-hand side, if reverse is selected) of each line is a representation that attempts to mimic the
way the curve is plotted. On the other side of each line is the text description (the line title), obtained
from the plot command. The lines are vertically arranged so that an imaginary straight line divides the
left- and right-hand sides of the key. It is the coordinates of the top of this line that are specified with
the set key command. In a plot, only the x and y coordinates are used to specify the line position. For
a splot, x, y and z are all used as a 3D location mapped using the same mapping as the graph itself to
form the required 2D screen position of the imaginary line.
When using the TeX or PostScript drivers, or similar drivers where formatting information is embedded
in the string, gnuplot is unable to calculate correctly the width of the string for key positioning. If
the key is to be positioned at the left, it may be convenient to use the combination set key left Left
reverse. The box and gap in the grid will be the width of the literal string.
If splot is being used to draw contours, the contour labels will be listed in the key. If the alignment of
these labels is poor or a different number of decimal places is desired, the label format can be specified.
See set clabel (p. 91) for details.
Examples:
This places the key at the default location:
set key default
This disables the key:
unset key
This places a key at coordinates 2,3.5,2 in the default (first) coordinate system:
set key at 2,3.5,2
This places the key below the graph:
set key below
This places the key in the bottom left corner, left-justifies the text, gives it a title, and draws a box
around it in linetype 3:
set key left bottom Left title ’Legend’ box 3