#set TITLE = "input data formats"
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.SH DESCRIPTION
Plotting is driven by data.  The
plot data may be specified within a ploticus script, or it may
be contained in a file, or be the result of executing a shell command.
\fBproc getdata\fR is used to specify or read in plotting data.
.LP
Ploticus uses \fBfield-oriented\fR data.  Most plotting is done
based on fields.  For example, a bargraph can be rendered based
upon the values in field #2 of each row of data.  A set of data
should contain one or more rows (lines).
.LP
Fields may be delimited in one of three ways.  
The delimitation must be specified in \fBproc getdata\fR.
The three ways are:
.IP \(bu
\fBwhite-space\fR (any combination of spaces or tabs)
.IP \(bu
\fBcomma\fR (often called spreadsheet or .csv)
.IP \(bu
\fBtab\fR 
.LP
Fields may be surrounded by \fB"double quotes"\fR; this must be done
when a field contains embedded delimiter characters.
.LP
The number of fields should be consistent across records.
.LP
A comment character (specified as a \fBproc getdata\fR attribute) 
may be given as the first character
on a line; it causes that line to be ignored.
.LP
Beginning in version 1.40 it is possible to set ploticus variables from within
a data file using the construct: \fC#set VARIABLE = value\fR.

.SH EXAMPLES
Gallery examples include:
.br
.ig >>
<a href="../gallery/scat7.dat">
.>>
scat7.dat
.ig >>
</a>
.>>
(white-space delimited)
.br
.ig >>
<a href="../gallery/stock.csv">
.>>
stock.csv
.ig >>
</a>
.>>
(comma delimited)
.br
.ig >>
<a href="../gallery/timeline3.htm">
.>>
timeline3
.ig >>
</a>
.>>
(data specified within script)
.br
.ig >>
<a href="../gallery/km2.htm">
.>>
km2
.ig >>
</a>
.>>
(data specified within script).


.SH DETAILS
.LP
The plotting procedures generally access specific fields and process 
the data from top to bottom.  For example, a bar graph might be made
by drawing one bar for each data record based on the value
in field 2.
.LP
.ig >>
<a href="getdata.html">
.>>
Proc getdata
.ig >>
</a>
.>>
is used to read in a data file for plotting.
After \fBproc getdata\fR has been executed,
the plotting procedures can access the data by 
record and field.

#include space

.SH HANDLING MISSING DATA
Ploticus can handle missing plot data values.
In data sets that are to be plotted, missing items
should be denoted by a value that is not plottable, e.g.
for numeric data, a value that is non-numeric.
The plotting procedures omit non-plottable values (the details of
how this is handled are given in the man page for each plotting proc).
An Gallery example involving missing numeric data represented 
by dashes(-) is
.ig >>
<a href="../gallery/volunteers.htm">
.>>
volunteers 
.ig >>
</a>
.>>

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