## Introduction to ploticus scripts

Version 2.32
Scripts

Manual page for Introduction_to_ploticus_scripts(PL)

Ploticus is controlled by scripts that a user creates in a text editor and saves in a file.`` Script files should be plain ascii text files, and they may be named anything, however a file name ending of .p, .pl, .plo, or .pls is recommended.``

Note that for many uses you don't need to write a script at all.. you can use a ploticus prefab, and control the plot by supplying some parameters on the command line while everything else is handled automatically. Scripts are useful when customization is needed, or for doing more sophisticated operations like multiple plots, overlays, data manipulation and processing, or for graph types where a prefab doesn't exist.``

## Simple example

     // simple example 1

     #proc areadef
       rectangle: 1 1 4 2
       xrange: 0 5
       yrange: 0 100

     #proc xaxis:
       stubs: text
     	Africa
     	Americas
     	Asia
     	Europe,\nAustralia,\n Pacific

     #proc yaxis
       label: Growth Rate
       stubs: inc 20
       minortics: yes
       minorticinc: 5

     #proc getdata
       data: 76
     	54
     	60
     	59

     #proc bars
       lenfield: 1
       color: teal
       barwidth: 0.2

As you can see, this is not low-level 3GL-style code. It is a sort of hybrid; plotting actions (#procs) are specified in procedural order, but within each #proc the language is goal-driven (4GL). Thus, traditional procedural programming skills are not required.``

The above ploticus script invokes a number of procedures (procs).`` First, proc areadef to set up a plotting area, then proc xaxis and yaxis to render the axes.`` Then proc getdata is invoked to define some data, and then finally proc bars is invoked to produce a bar graph.``

For each proc, the user may specify a various attributes or options.`` Attributes that are not specified use a default when possible.`` In the above example, the user has invoked `proc areadef` and specified values for these attributes: `rectangle`, `xrange`, and `yrange`. All of the procs, as well as the names, types, and acceptable values for all attributes, are described in the ploticus scripts handbook.``

## Another example

A typical use of ploticus is to display chronological data.`` Suppose we have some data in a file called `log.dat` that has fields `count` and `dt` like this:

      18 071301
      16 071401
      15 071501
      34 071601
      ...etc..

Here's a script that will automatically scale to the data and plot the values over time as shown above:

     // simple example 2

     #proc getdata
     file: ../pltestsuite/data19
     fieldnames: count dt

     #proc areadef
     rectangle: 1 1 5 3
     xscaletype: date mmddyy
     xautorange: datafield=dt
     yautorange: datafield=count incmult=2.0 lowfix=0
     xaxis.stubs: inc 1 month
     xaxis.stubformat: Mmmyy
     yaxis.stubs: inc

     #proc lineplot
     xfield: dt
     yfield: count
     linedetails: color=red

A large collection of script examples may be found in the ploticus scripts gallery.`` One way to proceed is to locate an example that is similar to what you want, and then copy it and play with it.``

Continue to Script Syntax page

data display engine
Copyright Steve Grubb

Markup created by unroff 1.0, `` `` August 23, 2005.