realead / pseudopol

a collection of algorithms for pseudo polynomial problems

pseudopol

a collection of algorithms for pseudo polynomial problems

Installation

This module can be used by python2.7 and python3. The easiest way to install/test is to use virtual environment (here for python2.7):

virtualenv -p python2.7 p27
source p27/bin/activate
(p27) ...

Right now cython-tool-chain is needed for installation:

(p27)pip install cython

Now the current version can be installed from github:

(p27) pip install https://github.com/realead/pseudopol/zipball/master

It is possible to uninstall it afterwards via

(p27) pip uninstall pseudopol

You can also install using the setup.py file from the root directory of the project:

(p27) python setup.py install

However, there is no easy way to deinstall it afterwards (only manually) if setup.py was used directly.

You could also use the module without installation, by augmenting the python-path via enviroment variable

export PYTHONPATH="${PYTHONPATH}:<path_to_pseudopol>"

or programmatically, for example with help of

import sys
sys.path.append(path_to_exetest)

The same can be done for Python3.

Functionality

There are two sets of functions:

1. the pure python implementation, which can be found in module pseudopol.ppseudopol
2. fast C-implementation which can be found in pseudopol.cpseudopol

find_max_subsum

Given the values of objects Oi i=1...n, find a subsum S=sum Oi for i from I - a subset of {1...n} which is maximal and <= some given maximal value max_val.

Properties:

1. c-version needs around 1bit times max_val, python version around 80bytes, i.e. 640 times more (actually unclear why)
2. Time complexity O(n*max_val), c-version is about 1000 times faster than the python version (bit-tricks possible).

zerosum_subset_exists

Given the values of objects Oi i=1...n, find a non-empty subset where the sum of elements is 0.

Testing

The test scripts are in folder tests. Call

sh run_test_from_src.sh rebuild N

for running all (unit) tests using the current sources. Skip rebuild if rebuild of the extensions isn't needed. N gives the number of random tests and can be simply omited.

Run

sh test_install.sh PYTHON_VERSION 

to create a new virtual environment, install cython and pseudopol from the source and run all unit tests using this installation. Choose PYTHON_VERSION=p2 for python 2 or p3 for python 3.

By calling

sh test_install.sh PYTHON_VERSION from-git

the installed pseudopol version isn't from the current source, but will be downloaded from the git-repository.

History

0.1.0 find_max_subsum 0.2.0 zerosum_subset_exists // bug fixes