.TH d.linegraph
.SH NAME
\fId.linegraph \fR\- Generates and displays simple line graphs in the active
graphics monitor display frame.
.br
.I "(GRASS Display Program)"
.SH SYNOPSIS
\fBd.linegraph\fR
.br
\fBd.linegraph help\fR
.br
\fBd.linegraph \fBx_file\*=\fIname\fR  \fBy_file\*=\fIname\fR[,\fIname\fR,...] \fR[\fBdirectory\*=\fIname\fR] [\fBy_color\*=\fIoption\fR[,\fIoption\fR,...]\fR] [\fBx_title\*=\fIvalue\fR] [\fBy_title\*=\fIvalue\fR] [\fBtitle\*=\fIvalue\fR] [\fBtitle_color\*=\fIoption\fR] 
.SH DESCRIPTION
\fId.linegraph\fR is a primitive program to draw simple x,y line graphs 
based on numerical data contained in separate files.  
.LP
\fBParameters:\fR
.IP \fBx_file\*=\fIname\fR 8
Name of file with data for the X axis of graph.
.IP \fBy_file\*=\fIname\fR[,\fIname\fR,...] 8
Name of file(s) with data for the Y axis of graph. Up to ten Y inputs can be 
used.
.br
.PP 
\fIData file format\fR 
.br
The X and Y data files for the graph are essentially a column of numbers in each
file, with one input number per line. 
The program expects that each X value will have a corresponding Y value,
therefore the number of lines in each data input file should be the same.
Essentially, the X data becomes the X axis reference to which the
Y data is plotted as a line. Therefore, the X data should be a
monotonically increasing progression of numbers 
(\fIi.e. "1,2,3,..."; "0, 10, 100, 1000,..."; "...-5,-1,0,1,5..."\fR).
If multiple Y data files are used, the Y axis scale will be based on the
range of minimum and maximum values from all Y files, then all Y data given will
be graphed according to that Y scale. Therefore, if multiple Y data inputs are
used with dissimilar units, the graph produced comparing the two will be
deceptive.
.IP \fBdirectory\*=\fIname\fR 8
Path to the directory where the input files are located. If this option is not
used, the \fId.linegraph\fR looks for files in the current directory.
Example format: \fBdirectory\*=\fI/usr/grass/data/graph\fR
.IP \fBy_color\*=\fIoption\fR[,\fIoption\fR,...]\fR] 8
Color to be used for drawing the lines in the graph. If multiple Y data
files are used, an \fBequal\fR number of colors may be used to control
the colors of the lines. Colors will be assigned to Y data in respect
to the sequence of instantiation on the command line. Options are
listed below. By default, a series of colors will be chosen by the
program if none are provided upon invocation. (Order of default
colors: \fIyellow, red, green, violet, blue,
orange, gray, brown, magenta, white, indigo\fR).
.IP \fBtitle_color\*=\fIoption\fR 8
The color to be used for titles, axis lines, tics, and scale numbers.
Default is "\fIwhite\fR".
.br
.PP
\fIColor options:\fR red, orange, yellow, green, blue, indigo, violet,
magenta, brown, gray, white, and black.
.IP \fBx_title\*=\fIvalue\fR 8
Title to describe X data. Will be centered beneath the graph. Default
is no title unless the need for a unit descriptor is computed by the 
program (i.e. X: \fBtitle\fI in hundreds\fR). Also, see \fBNOTES\fR 
section (below) for a format caveat for
multi-word titles.
.IP \fBy_title\*=\fIvalue\fR 8
Title to describe Y data. Will be centered beneath the X data title.
Default is no title unless the need for a unit descriptor is computed by the 
program (i.e. Y: \fBtitle\fI in thousands\fR). Also, see \fBNOTES\fR section 
(below) for a format caveat for
multi-word titles. In the case of graphs with multiple lines, one
may wish to use more specific title placement by using the
\fBd.text\fR or \fBd.label\fR programs.
.IP \fBtitle\*=\fIvalue\fR 8
Title to describe the graph. Will be centered over the top of graph.
Default is no title. See \fBNOTES\fR section (below) for a format caveat for
multi-word titles.
.br
.SH "NOTES"
Since the command line parser is not amiable to multiple word
inputs, to input titles of more than one word, use the underscore
character ("_") to represent spaces (" "). Example:
"\fBtitle\*=\fICensus_data_1990\fR" would be printed over the graph as
"\fICensus data 1990\fR".

The way the program locates and labels tic marks is less than perfect:
1) although distances between Y tics is proportional to the value,
they are not proportional on the X axis; 2) decimal values between -1 and
1 can be printed on the X axis, but not on Y. (With respect to the 
later, the input for Y values can all be multiplied by a factor of 10
before graphing).
.br
.SH "BUGS"
No doubt.
.SH "SEE ALSO"
.I d.INTRO,
.I d.frame,
.I d.text,
.I d.label,
and
.I parser
.SH "AUTHOR"
Chris Rewerts, Agricultural Engineering, Purdue University
