"""
This module defines the methods for social community detection.
"""
[docs]def get_groups(
a_graph,
method='component_infomap', return_form='membership'):
"""
Return the grouping of the provided graph object using the specified
method. The grouping is returned as a list of sets each holding all
members of a group.
Parameters
==========
a_graph: :class:`igraph.Graph`
The graph to partition
method: str (default='component_infomap')
String specifying which method to use. If two methods
should be used one after the other they should be separated by `_`.
Default: 'component_infomap' which will first consider all
disconnected components as groups then apply infomap on all of
those groups to optionally further split.
return_form: str (default='membership')
Determines the format of how the social group structure should be
returned. Options are:
* ``'membership'``: A list returning for each `index` node the group it
belongs to.
* ``'memberlists'``: Dictionary with a list of members `value` for each
group `key`.
Returns
=======
dict
Depending on what was chosen for the `return_form` attribute, either the
membership dict, i.e.::
{
node_id: group_id,
...
}
or the memberlist dict, i.e.::
{
group_id: [node1_id, node2_id, ...],
...
}
(value) is returned.
"""
# methods = method.split('_')
# For now only 'component_infomap' is allowed as procedure
if method == 'component_infomap':
# first the connected components
a_graph.vs['component'] = a_graph.clusters(
).membership
components = set(a_graph.vs['component'])
# create for each component a graph and apply infomap to it
node_membership = {}
# print(
# 'INFO: Found {0} disconnected components'.format(len(components))
# )
if components:
# do the community detection on each component and create a
# compound group id: component_group
for component in components:
_comp_graph = a_graph.subgraph(
[
node['name']
for node in a_graph.vs
if node['component'] == component
]
)
_infompa_comp_graph = _comp_graph.community_infomap('weight')
_comp_graph.vs['_group'] = _infompa_comp_graph.membership
for node in _comp_graph.vs:
node_membership[node['name']] = '{0}_{1}'.format(
node['component'], node['_group']
)
del _infompa_comp_graph
else:
_infompa_comp_graph = a_graph.community_infomap('weight')
a_graph.vs['group'] = _infompa_comp_graph.membership
node_membership = {
node['name']: node['group']
for node in a_graph.vs
}
group_membership = {}
for node in node_membership:
try:
group_membership[node_membership[node]].append(node)
except KeyError:
group_membership[node_membership[node]] = [node]
if return_form == 'membership':
# nbr_nodes = len(a_graph.vs['name'])
# membership = [None]*nbr_nodes
# for g, members in group_membership.items():
# for member in members:
# membership[member] = g
# return membership
return node_membership
elif return_form == 'memberlists':
# return [_group for _group in group_membership.values()]
return group_membership
else:
return None
