# Overview

## Delny

This package contains some Python modules for Delaunay triangulation using the Qhull C library libqhull.

## Prerequisites

Before the installation you will need an installation of qhull 2003.1 including it's header files and libqhull in the standard locations for your system. The _qhull module is an extension module and needs this to compile.

Next the numpy module for Python should be available, also including it's development files in the standard locations. Note that setup.py import numpy to find the relevant C include directories, so even to run setup.py you will need numpy to be available.

And of course a proper Python installation with the header files and other development files.

For Debian and Ubuntu these are the packages you want, some may depend on each other: python python-dev python-numpy libqhull5 libqhull-dev

## Installation

Delny uses the Distutils, so to install run

$./setup install from within Delny's root directory. Or to install in your home directory for example, make sure ~/lib/pyton exists and is included in your Python path (by setting the PYTHONPATH environment variable for instance) and run:$ ./setup install --home=~

For more information on the installation (recommended!) using Distutils use:

$./setup --help Extensive online Distutils documentation for sysadmins can be found on http://www.python.org/inst/inst.html ## Testing the installation Tests are included under the subdirectory test'. Files testing an individual module name "module" will be called "test_module", to test all modules at once there is a convenience script all.py'. If you want to run them make sure the correct delaunay' package will get imported (see NOTE under "Using Delny" below), so to test a recent build e.g.:$ ./setup build $cd build/lib.linux-i686-2.3 # or whichever dir for your setup$ ../../test/all.py

If tests fail be sure to check the BUGS' file to see if there is any information about them.

## Using Delny

Once installed, information on how to use is available from within Python as:

import delaunay help(delaunay)

NOTE: when the current directory is the package root the Python interpreter will import the Delaunay package form there instead as from the installed location because it comes first in sys.path. This results in an error as __init__.py tries to load the _qhull module which is not available there as it is provided by _qhull.so which is only in the build/ directory and in it's installed directory. Make sure you are using the package with the compiled extension module.

## Changes in 0.4.1

• Fix numpy transition, the python code was still using numeric.
• Get the numpy installation directory from numpy, instead of assuming it will be in a system-default location.
• Use the Qz option so the 2D square works, remove the extra vertex from the output so it's transparent to the user.

## Upgrading to 0.4.0

The only change is to use the numpy package instead of numeric. No other changes where made.

## Upgrading from pre 0.2.0

No incompatible API changes where made. Only the delaunay.facets_indices() method has been added. Most changes where internally inside the _qhull module which is now much cleaner and more flexible.

Note that there is still no guaranteed API stability as long as 1.0 is not reached. In fact changes are still planned.

The new versioning sheme doesn't use the a' or b' suffixes anymore for alpha or beta. Just know that there's no stability untill 1.0 is reached. The alpha and beta releases may come back when 1.0 is reached or just before.

## Upgrading from pre 0.1.0a2

Please note the API changes, this is still alpha so you should have know this would happen.

Basically: (i) the package name is changed to "delaunay" (formerly "Delaunay"). (ii) the format for method (and function) names has changed. Wat formally was "get_this_stuff()" is now "getThisStuff()". (iii) the tests have moved to the directory which they are testing, that is "Delny-xxx/tests/" has moved to "Delny-xxx/delaunay/tests/"

As always, hopefully these things won't change anymore...

## Using qhull3.1

When using qhull3.1 it will be necessary to modify the delaunay/_qhullmodule.c file. Near the top you will see a line where #define QHULL_31_COMP=1 is commented out, uncomment this and it should work for qhull3.1. A more automated way for this is envisioned for a future release.

Please note that any earlier version of qhull does not support triangulated output (Qt) and thus will not normally work with Delny, qhull3.1 is the oldest version you can use.

## Feedback

Please send feedback and bug reports to floris.bruynooghe@gmail.com.

## Authors

This package was written by Floris Bruynooghe (floris.bruynooghe@gmail.com). Ola Skavhaug <skavhaug@simula.no> contributed the initial patch for referring to nodes by index.