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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>How to use the OCaml bindings</title><link rel="stylesheet" type="text/css" href="stylesheet.css"><meta name="generator" content="DocBook XSL Stylesheets V1.79.1"><link rel="home" href="index.html" title="Documentation of the PLplot plotting software"><link rel="up" href="OCaml.html" title="Chapter 11. OCaml Language"><link rel="prev" href="ocaml_obtaining.html" title="Obtaining the Software"><link rel="next" href="ocaml_known_issues.html" title="Known Issues"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">How to use the OCaml bindings</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ocaml_obtaining.html">Prev</a> </td><th width="60%" align="center">Chapter 11. OCaml Language</th><td width="20%" align="right"> <a accesskey="n" href="ocaml_known_issues.html">Next</a></td></tr></table><hr></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="ocaml_howto"></a>How to use the OCaml bindings</h2></div></div></div><p>
The three examples provided below illustrate the available methods for
generating plots with PLplot from OCaml. They proceed in order from
lowest-level to highest-level.
</p><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="ocaml_findlib_setup"></a>How to setup findlib for use with the OCaml bindings</h3></div></div></div><p>
The following examples require that
<a class="ulink" href="http://projects.camlcity.org/projects/findlib.html" target="_top">
findlib
</a>
and its associated tools (i.e., ocamlfind) are installed in in your
<code class="literal">$PATH</code>.
</p><p>
If PLplot was installed under a non-standard prefix, or any prefix
where findlib does not check automatically for OCaml libraries, then
the following environment variables can be set to tell findlib where to
look for PLplot:
</p><pre class="programlisting">
export OCAMLPATH=$PLPLOT_INSTALL_PREFIX/lib/ocaml:$OCAMLPATH
export LD_LIBRARY_PATH=$PLPLOT_INSTALL_PREFIX/lib/ocaml/stublibs:$LD_LIBRARY_PATH
</pre></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="ocaml_command_line_sample_project_core"></a>Sample command line project (core API)</h3></div></div></div><p>
Here is a simple example that can be compiled and run from the command
line. The result will be a program that generates a plot of part of a
parabola using only the core PLplot API.
</p><pre class="programlisting">
(* Open the Plplot module to give access to all of the PLplot
values without the need to add the "Plplot." prefix. *)
open Plplot
let simple_example () =
(* Sample at 20 points, ranging from -10.0 to 10.0 *)
let xs = Array.init 21 (fun xi -> float xi -. 10.0) in
let ys = Array.map (fun x -> x**2.0) xs in
(* Initialize PLplot *)
plinit ();
(* Draw the plot window axes *)
plenv (-10.0) 10.0 0.0 100.0 0 0;
(* Draw the parabola points as a series of line segments *)
plline xs ys;
(* End the plotting session *)
plend ();
()
let () = simple_example ()
</pre><p>
Save this code as <code class="literal">simple_example_core.ml</code>. The
following command can then be used to build the example:
</p><pre class="programlisting">
ocamlfind opt -package plplot -linkpkg -o simple_example_core simple_example_core.ml
</pre><p>
The resulting binary program can be run by typing
<code class="literal">./simple_example_core</code>
</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="ocaml_command_line_sample_project_ocaml"></a>Sample command line project (OCaml-specific API)</h3></div></div></div><p>
Here is another example that can be compiled and run from the command
line. The result will be a program that generates a plot of part of a
parabola similar to the above example, but now using the
OCaml-specific PLplot API rather than the core PLplot API.
</p><pre class="programlisting">
(* Open the Plplot module to give access to all of the PLplot
values without the need to add the "Plplot." prefix.
Aliasing the module P to the module Plot will save some typing
without further namespace pollution. *)
open Plplot
module P = Plot
let simple_example () =
(* Initialize a new plot, using the windowed Cairo device
("xcairo") *)
let p =
P.init (-10.0, 0.0) (10.0, 100.0) `greedy (`window `cairo)
in
(* Draw the parabola *)
P.plot ~stream:p [P.func `blue (fun x -> x ** 2.0) (-10.0, 10.0)];
(* Draw the plot axes and close up the plot stream using the default
spacing between tick marks. *)
P.finish ~stream:p ();
()
let () = simple_example ()
</pre><p>
Save this code as <code class="literal">simple_example_ocaml.ml</code>. The
following command can then be used to build the example:
</p><pre class="programlisting">
ocamlfind opt -package plplot -linkpkg -o simple_example_ocaml simple_example_ocaml.ml
</pre><p>
The resulting binary program can be run by typing
<code class="literal">./simple_example_ocaml</code>
</p></div><div class="sect2"><div class="titlepage"><div><div><h3 class="title"><a name="ocaml_toplevel_sample_project"></a>Sample toplevel project</h3></div></div></div><p>
The OCaml interactive toplevel (<code class="literal">ocaml</code>) provides a
very useful tool for code testing, development and interactive data
analysis.
</p><p>
The <code class="literal">Quick_plot</code> module provides a set of functions
for producing quick, simple two-dimensional plots from both the
toplevel and stand-alone OCaml programs. Here is a set of commands
which can be used in a toplevel session to produce a plot of a portion
of a parabola, similar to the compiled examples above.
</p><pre class="programlisting">
# #use "topfind";;
# #require "plplot";;
# open Plplot;;
# Quick_plot.func ~names:["Parabola"] [(fun x -> x ** 2.0)] (-10.0, 10.0);;
</pre><p>
Conversely, the above <code class="literal">ocaml</code> session could be
expressed in a compiled OCaml program:
</p><pre class="programlisting">
Plplot.Quick_plot.func ~names:["Parabola"] [(fun x -> x ** 2.0)] (-10.0, 10.0)
</pre><p>
Save this code as <code class="literal">simple_example_quick.ml</code>. The
following command can then be used to build the example:
</p><pre class="programlisting">
ocamlfind opt -package plplot -linkpkg -o simple_example_quick simple_example_quick.ml
</pre><p>
The resulting binary program can be run by typing
<code class="literal">./simple_example_quick</code>
</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ocaml_obtaining.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="OCaml.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ocaml_known_issues.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Obtaining the Software </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Known Issues</td></tr></table></div></body></html>
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