qstest 1.1.0

Python code for the (q,s)-test

Python codes for the (q, s)-test, a significance test for individual communities in networks.

Please cite

Kojaku, S. and Masuda, N. "A generalised significance test for individual communities in networks". Preprint arXiv: 1712.00298 (2017)
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Contents

LICENSE - License of qstest

README.md - README file for Github

README.txt - This README file

setup.py - Script for installing qstest

requirements.txt - List of libraries installed by setup.py

test.py - Test code for Travis CI

.gitignore - Configuration file for GitHub

.travis.yml - Configuration file for Travis CI

qstest/ - Python codes for the (q, s)-test:

qstest/__init__.py - Header file

qstest/cdalgorithm_wrapper.py - Codes for community-detection algorithms

qstest/qstest.py contains - Codes for the (q, s)-test

qstest/quality_functions.py - Codes for calculating quality functions of a community

qstest/size_functions.py - Codes for calculating the size of a community

examples/ - example codes:

examples/example1.py - Usage of qstest with a built-in quality function, community-size function and community detection algorithm

examples/example2.py - Usage of qstest with a user-defined quality function

examples/example3.py - Usage of qstest with a user-defined community-size function

examples/example4.py - Usage of qstest with a user-defined community-detection algorithm
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Installation

You can install qstest with pip, a package management system for Python.

To install, run

pip install qstest

If this does not work, try

python setup.py install
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Usage

sg, p_values = qstest(network, communities, qfunc, sfunc, cdalgorithm, num_of_rand_net = 500, alpha = 0.05, num_of_thread = 4)

Input

network - Networkx Graph class instance

communities - C-dimensional list of lists. communities[c] is a list containing the IDs of nodes belonging to community c. Node and community indices start from 0.

qfunc - Quality of a community. The following quality functions are available:

qmod - Contribution of a community to the modularity

qint - Internal average degree

qexp - Expansion　
　
qcnd - Conductance　

To pass your quality function to qstest, see "How to pass your quality function to qstest" below.

sfunc - Community-size function (i.e., size of a community). The following community-size functions are available:

n - Number of nodes in a community

vol - Sum of the degrees of nodes in a community

To pass your community-size function to qstest, see "How to pass your community-size function to qstest" below.

cdalgorithm - Community-detection algorithm. The following algorithms are available:

louvain - Louvain algorithm (http://perso.crans.org/aynaud/communities/index.html)

label_propagation - Label propagation algorithm (https://networkx.github.io/documentation/stable/reference/algorithms/community.html)

To pass your community-detection algorithm to qstest, see "How to pass your community-detection algorithm to qstest" below.

num_of_rand_net (optional) - Number of randomised networks (Default: 500)

alpha (optional) - Statistical significance level before the Šidák correction (Default: 0.05)

num_of_thread (optional) - Maximum number of CPU threads (Default: 4)

Output

sg - Results of the significance test (C-dimensional list). sg[c] = True or False indicates that community c is significant or insignificant, respectively.

p_values - P-values for the communities (C-dimensional list). p_values[c] is the p-value for community c.

Example (examples/example1.py)

import networkx as nx
import qstest as qs

network = nx.karate_club_graph()
communities = qs.louvain(network)
sg, p_values = qs.qstest(network, communities, qs.qmod, qs.vol, qs.louvain)
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How to pass your quality function to qstest

Write a quality function of a community as follows:

q = my_qfunc(network, community)

Input

network - Networkx Graph class instance

community - List of nodes belonging to a community

Output

q - Quality of the community

Then, pass my_qfunc to qstest:

sg, p_values = qstest(network, communities, my_qfunc, sfunc, cdalgorithm)

Example (examples/example2.py)

import networkx as nx
import qstest as qs

# Number of intra-community edges
def my_qfunc(network, nodes):
return network.subgraph(nodes).size()

network = nx.karate_club_graph()
communities = qs.louvain(network)
sg, p_values = qs.qstest(network, communities, my_qfunc, qs.vol, qs.louvain)
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How to pass your community-size function to qstest

Write a community-size function of a community as follows:

s = my_sfunc(network, community)

Input

network - Networkx Graph class instance

community - List of the IDs of nodes belonging to a community

Output

s - Size of the community

Then, pass my_sfunc to qstest:

sg, p_values = qstest(network, communities, qfunc, my_sfunc, cdalgorithm)

Example (examples/example3.py)

import networkx as nx
import qstest as qs

# Square of the number of nodes in a community
def my_sfunc(network, nodes):
return len(nodes) * len(nodes)

network = nx.karate_club_graph()
communities = qs.louvain(network)
sg, p_values = qs.qstest(network, communities, qs.qmod, my_sfunc, qs.louvain)
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How to pass your community-detection algorithm to qstest

To pass your community-detection algorithm to qstest, write a wrapper function of the following form:

communities = my_cdalgorithm(network)

Input

network - Networkx Graph class instance

Output

communities - C-dimensional list of lists. communities[c] is a list containing the IDs of nodes belonging to community c.

Then, pass my_cdalgorithm to qstest:

sg, p_values = qstest(network, communities, qfunc, sfunc, my_cdalgorithm)

If the community-detection algorithm requires parameters such as the number of communities, then pass the parameters as global variables, e.g., define a global variable X, then use X within the cdalgorithm.

Example (examples/example4.py)

import networkx as nx
import qstest as qs
from networkx.algorithms import community as nxcdalgorithm

# Wrapper function for async_fluidc implemented in Networkx 2.0
def my_cdalgorithm(network):
communities = []
subnets = nx.connected_component_subgraphs(network)
for subnet in subnets:
coms_iter = nxcdalgorithm.asyn_fluidc(subnet, min([C, subnet.order()]), maxiter)
for nodes in iter(coms_iter):
communities.append(list(nodes))
return communities

# Pareameters of async_fluidc
C = 3
maxiter = 10

network = nx.karate_club_graph()
communities = my_cdalgorithm(network)
sg, p_values = qs.qstest(network, communities, qs.qmod, qs.vol, my_cdalgorithm)
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Requirements

Python 2.7, 3.4 or later

SciPy 1.0 or later

Networkx 2.0 or later

python-louvain 0.9
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Last updated: 29 November 2017