Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [igraph]

igraph is a collection of tools for graph theory and network analysis. Its core is a software library written in C/C++, and it has interfaces to R, Python and Mathematica.

igraph is a collection of network analysis tools with the emphasis on efficiency, portability and ease of use. igraph is open source and free. igraph can be programmed in R, Python, Mathematica and C/C++.

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63 questions
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Centralization measures in weighted graphs

I'm using the igraph package in R to analyze network data. I'm currently trying to calculate some centrality measures for the vertices of my graph and the corresponding centralization scores. My network is both directed and…
Patrick S. Forscher
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Force-directed methods to draw graphs

i am working to create a mapping of the adjacencies between 100 consumer goods. I have created an adjacency matrix based on product characteristics, and then create an i-graph of the graph/network (using tkplot / igraph) I am using the fruchterman…
Wouter
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Newman's modularity clustering for graphs

I am interested in running Newman's modularity clustering algorithm on a large graph. If you can point me to a library (or R package, etc) that implements it I would be most grateful.
laramichaels
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Graph clustering algorithms which consider negative weights

I have a graph instance with weighted directed edges which values can be in range [-1,1]. I need to do clustering on this graph, in order to find out groups in which vertices are more correlated. I searched for several clustering or community…
Ewybe
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Interpreting output of igraph's fastgreedy.community clustering method

With the help of several people in this community I have been wetting my feet in clustering some social network data using igraph's implementation of modularity-based clustering. I am having some trouble interpreting the output of this routine and…
laramichaels
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igraph betweenness depends on order of edges

I have a question whether order of edges in graph should matter or not? It seems that betweenness function produces slightly different results for different orderings of input file. input file : http://preview.tinyurl.com/p9vlxnc #1st run, with…
Vitomir Kovanovic
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Explanation of centralityPlot in qgraph

I am using this code to get a centralityPlot. library(qgraph) centralityPlot(graph2, include = c("Strength","ExpectedInfluence","Betweenness","Closeness"), orderBy ="ExpectedInfluence") Outcome from RStudio: Can…
Nikkimarie Björkenberg Glenn
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Clustering network usign modularity maximization algorithm

I have been working on a Network-based clustering approach. I used "cluster_optimal" of 'igraph' package in R for clustering. The function works by modularity maximization algorithm. I have understood the concept of modularity (Newman, 2006). But I…
Bloodstone Programmer
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Calculating Transitivity (Clustering Coefficient) from Adjacency Matrix, and igraph package

Suppose $G$ is a simple, undirected graph. The corresponding adjacency matrix, $A$ is binary, symmetric, and has all zeroes on the diagonal. By definition (Networks: An Introduction, M.E.J Newman), the clustering coefficient $C$ is given by…
RMurphy
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Community detection and modularity

I am reading the book "Network science" of Barabasi and in particular the chapter on community detection. If I understand correctly, modularity is a goodness factor of partition calculated by a certain algorithm: the greater the value of modularity…
marielle
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Problems with representing and analysing non-network data as a network?

Suppose I have a dataset with 200 observations of 30 categorical variables. The dataset describes websites and different kinds of design features they deploy (or do not deploy). If I were to convert this into a network format (for example, using the…
timothyjgraham
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techniques for sampling graphs? (possibly implemented in r packages)

Let's say I have a very large graph that proves impractical for visualization ends and I wanted to sample a random subgraph. (I know that I can filter out a subgraph via measures like degree, components, weights... but this is not my point) Is there…
Dario Lacan
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Plot directed acyclic graph with scaled edge length

I am trying to design a network (more precisely a directed acyclic graph) with specific edge lengths. The data is on the form of an edge list, and for each edge, there is an associated length. It might take the form of an edgelist matrix and a…
Jean-Baptiste Camps
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Build graph of transitive relationships

I am wondering given the type of directed graph A, how do I convert it into the type of directed graph B? Basically, in graph B, I want to ignore Node X and only retain the Node T. Conceptually, I am not sure if there are any ways to construct the…
flashing sweep
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Community-detection algorithm to use to divide large network (200k nodes) into few (~5) communities

I have a large moderately dense network (50k nodes, 300k edges) and want to divide this into few (5-10) communities, based on how densely connected the nodes are. I've been looking into the algorithms available in R's igraph-package and while they…
sheß
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