Available prefabs
chron - chronological data (dates, times, etc); tabulate by week, month, etc.
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dist - frequency distribution histogram on a data field
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lines - line plots with optional data points and error bars, up to 4 groups
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pie - pie graphs
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stack - stacked bar graphs, up to 4 levels |
scat - scatterplots
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vbars - bar graph of 1 or 2 groups with error bars
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vbars - with error bars only
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Also available:
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draw
for interpreting ploticus draw commands
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multidist
user-contributed prefab that does multiple, overlaid frequency distributions.
What are prefabs?
Prefabs are the easiest way to get started with ploticus.
You can quickly generate common types of plots without needing to code a ploticus script.
Just supply several key parameters on the command line or in the data file.
Everything else uses defaults.
The -prefab command line option tells pl to use a prefab.
Any of the other command options may also be used along with -prefab.
For example, to use the scat scatterplot prefab you might use
a command such as this:
-
-
pl -prefab scat -png data=results.dat x=2 y=4 -scale 0.7
What do I need to do before I begin?
Prefabs work by invoking special ploticus scripts that have been generalized
to accept various parameters.
These scripts are included with ploticus in the ./prefabs directory.
You can use this directory or set up one of your own.
So that ploticus can find these files,
you must supply the full path name of the directory in an environment variable called PLOTICUS_PREFABS
(alternatively this may be hard-coded at build time, settable in the Makefile as PREFABS_DIR).
Which parts of the ploticus documentation do I need to look at?
Prefab users should find most of what they need to know from this page along with
the first three sections of the
ploticus handbook.
Prefabs are a higher-level interface to the functionality available in scripts, so there may
be an occational need to jump into the other documentation for certain particulars.
Will I outgrow prefabs?
Prefabs are intended to cover common, straightforward situations.
By their very nature, prefabs do not offer the flexibility that's available
with scripts. If you work with prefabs for a while you will probably encounter
something that you can't do with prefabs, but could do with a script.
At this point I recommend making the jump to script coding; it's not really
that hard if you learn by looking at the examples.
Passing parameters to a prefab
Parameters may be supplied on the pl command line as var=value
pairs as seen in the above example.
There is a set of
standard parameters
that are recognized by all the prefabs unless otherwise noted; it is useful to become familiar with these.
Individual prefabs also have parameters of their own.
If convenient, most parameters may be embedded in an input
data file, using the #set construct:
-
-
#set x = 2
#set y = 3
#set title = Correlation of WBC vs. T-Chol
Some parameters cannot be set from within the data file because they control
data scanning. These are data, delim, header, and comment.
There may be others as noted for individual prefabs.
Output file names
The -o option may be used to specify output file name explicitly.
If -o is not given,
output file naming is similar to that of pl in other contexts.
For the above example the output file would be named scat.png .
Plot data
Plot data must be located in a file.
The name of the data file is given in the
data= parameter
the data field delimitation method may be given in the
delim= parameter
. See
dataformat
for more information on acceptable data formats.
Missing data fields are generally skipped, but this depends
on what kind of plot is being generated. See
dataformat
for more discussion of missing data.
Customization
Prefabs allow quick looks at data, but
there are often details that would be nice to control
but can't be adjusted because there is no command line parameter to do so.
One way to proceed is to copy a prefab script to your own directory and
then modify your copy as needed.
Another option is to make a new prefab variant in the prefabs directory.
If you just want different defaults for a prefab, you can create a shell script
that invokes the prefab as you want it. Then,
put a $* at the end of the pl
command to pick up any overrides that the shell script user enters
on the command line (if a parameter is given twice, the rightmost is taken).
Examples
All prefab examples are included in the ploticus test suite that is included
with all distributions (2.02 and later).
Hints
You can create a
ploticus config file
and use it to set prefab parameters that you always want to be in effect.
For example:
option: comment=#
option: delim=comma
It is possible to set parameters from within your data file using
embedded #set statements.
The following
pl command line options
may be very useful with prefabs:
-scale, -color, -backcolor, -tightcrop, -map,
-debug,
and perhaps -font.
Be careful not to confuse prefab parameters with
pl command line options
. Prefab parameters are given this way: paramname=value.
Command line options are given this way: -option or -option value.
Most shells allow a backslash (\) for breaking up long commands into two or more lines.
You can get a multi line title by splitting it over two lines, eg:
pl -prefab pie1 data=data1 fld=3 label=1 title="Travel expenditures
By department
Fiscal year 2000"
HTML clickmaps
may be generated using the prefab
clickmapurl standard parameter
.
User-contributed prefabs
User-contributed prefabs are welcome and may be sent to scg@jax.org;
please include the prefab script file and a man page giving at least one working example.
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