Questions tagged [networks]

Refers to network theory as part of the graph theory. For questions about neural networks, use our [neural-networks] tag.

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48 views

Request for references: Best way to estimate directed graphs *with* cycles

I have $n$ observations of $p$ random variables $\{Y_1,\dots,Y_p \}$. I know that each observation has been generated from a linear network model of the form $$ Y = WY+\epsilon $$ and that the graph ...
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31 views

How to sample undirected graph/network data?

I recently want to test my network estimation algorithms and need to sample some data from undirected graphs. The natural way I think of was: Generate a sparse symmetric Precision matrix $P$. ...
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71 views

Network analyses on probabilistic graphical models

I recently see examples of network analyses (such as centrality measures from network/graph theory) being applied on probabilistic graphical models (e.g. Gaussian graphical model) and there is a ...
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391 views

Network science: How to calculate assortativity (Pearson's correlation) coefficient for this small network?

Let $A$ denote a weighted, directed network, where the weights in the rows are the out-degrees, and weights in the columns are the in-degrees: $A$ = \begin{bmatrix} 0 & 0 & 0 \\ 1 &...
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1answer
58 views

Hidden layers neural networks [closed]

So I am designing a neural network which will decide which way a character should move and look. I was thinking of breaking it into two different networks one for movement and one for direction. So ...
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42 views

Consider a directed network as an undirected one for topology parameter comparisons

I have a set of biologically relevant transcriptional regulatory networks which are bipartite with a set of transcription factors and the genes that they regulate. However, when I put my network on ...
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2answers
2k views

Check for similarity between networks/graphs with the same nodes, but different edge values

I have two networks which involve the same entities, but the quantities around which I have built the respective networks are different. What is a good way to compare the networks? Currently, I run ...
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1answer
160 views

Any intuition for why eigenvector centrality relates to walks of infinite length?

Some centrality measures can be interpreted in terms of walks. Degree centrality relates to a walk of length one: The more walks of length one reach a node, the higher this centrality measure. ...
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1answer
114 views

Hypothesis testing for higher density in subsets of a network/graph

I have a network with over 40k nodes and about 12 million edges (float weights) and have about 10k subsets of this network that I want to test for increased density. I can think of the following ...
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234 views

Setting initial assignments for mixed-membership stochastic blockmodel

I created two networks at two points (in the middle of the month and at the end of the month). Tried to run mmsb.collapsed.gibbs.sampler for the first network and obtained network communities. However,...
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1answer
162 views

Difference between real and random graphs in bipartite networks

I am trying to prove that my network is a real network and not a random network by doing certain tests in igraph. The clustering coefficient of my network is zero, so I wont be looking at that ...
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25 views

Spatial autocorrelation in a correlation maxtrix

I have obtained species observation data from a spatially dense sampling scheme. I know from previous analyses that there is significant (residual) autocorrelation for some, but not all species of the ...
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1answer
46 views

Finding conversation blocks in group chat

While analysing an IM group chat, the aim is to create a network with nodes as the group participants and the links corresponding to their conversations. Assuming that this chat has conversation ...
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434 views

Clustering Coefficient of zero in the Network

The clustering co-efficient of my real network is zero. As a matter of fact, all the nodes of the network have a clustering coefficient of zero. I am trying to compare my network to an ensemble of ...
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113 views

Modeling products (from sales data) in a graph network for clustering and product recommendations.

I have a high level question about whether or not graph networks would be an appropriate method to model a situation I'm studying. It's been a while since I last worked on a project building/analyzing ...
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1answer
564 views

How to generate random networks for comparison with my network?

I have a network of 361 nodes and 695 edges. I want to prove that my network is statistically significantly different from a random network. Small-world connectivity is a key parameter that has been ...
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1answer
51 views

Is my network a real network [closed]

I have a network with a 361 nodes and 695 edges. My objective is to prove that my network is real and not a random connection of nodes like in the case of a random network. So, I did some research and ...
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1answer
378 views

Interpretation of Jaccard similarity for binary networks

Given two undirected networks with the same amount of nodes defined by $A_{ij}^1$ and $A_{ij}^2$, we take the unique unordered pairs $(i, j)$. After sorting them, we then have two binary vectors $\vec{...
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458 views

Input to fit a power-law to degree distribution of a network

I would like to use R to test whether the degree distribution of a network behave like a power-law with scale-free property. Nonetheless, I've read diferent people ...
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1answer
32 views

How to alter undirected, binary graph to have specific graph-analytical characteristics while keeping others constant

I am working on a undirected, binary graph (derived from functional neuroimaging). I would like to alter this graph to change specific graph-characteristics (e.g. a specific value for the global ...
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1answer
2k views

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), ...
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0answers
12 views

Term for node measure of flow importance

I'm looking for a term describing measures that relate to the importance of nodes/vertices in a graph in controlling flow. Nodes that sits in between dense clusters would be scored highly while highly ...
2
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1answer
197 views

Interpreting estimated parameter in Exponential Random Graph Model

I am estimating an exponential random graph model considering the following configurations: edges 2-stars 3-stars, and triangles However, my edges parameter is estimated to be a negative value, ...
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1answer
90 views

Measuring connectivity between clusters in an organizational network in R

I'm trying to conceptualize a network analysis problem and figure out where to start in terms of analysis techniques in R. Apologies as I'm fairly new to all this. Basically, I have a employee ...
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0answers
22 views

Finding correlation between size, weight and location in a network graph

I have an undirected graph of students, their friendship ratings, and amount of effort paid in class in the following format: ...
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0answers
230 views

How to decide if a relationship network(graph) is directed or undirected?

I have a dataset that consist of the following information: Person_1 (from node), Person_2 (to_node), Home_Room_Location (of person_1), Time_Spent_Together (treating this as weight). I've been ...
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94 views

Betweenness centrality - between two groups

I'm familiar with metrics of node centrality in a network. In particular betweenness centrality. Is there a metric that measures the betweenness of a node, for being in between 2 or more, pre-...
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2answers
286 views

Community detection in network

I'm fairly new to the subject of network theory and community detection, and I'm trying to apply to some data that I have. To start, my data essentially looks like this: Basically, what I have is a ...
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1answer
70 views

Finding Balance in Network of Friendships

I have a couple of data points on a large group of high school students: A: Who their Friends are B: Strength of Friendship for each friend (out of 5, 5 being best friends and 1 being acquaintances) ...
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0answers
68 views

Variational inference in the directed network in Airoldi's Mixed Membeship Stochastic Blockmodel

$\newcommand{\E}{\mathbb{E}}$I was dealing with derivations for the variational parameters in the model proposed by Airoldi, Blei, Fienberg, and Xing, 2008 for overlapping communities using a mixed-...
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135 views

Running an exponential random graph model (ERGM) with lagged covariates

at the moment I am trying to fit an exponential random graph model (ERGM) in R with the function 'ergm' that comes with the 'statnet' package. Here I have two questions. One is of technical nature and ...
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1answer
2k views

What is the relation between belief networks and Bayesian networks?

How are Bayesian networks related to deep belief networks? Are they the same? From the post What is the difference between a neural network and a deep belief network?, I gathered that deep belief ...
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0answers
125 views

How to explain conditional independence between two nodes in a Bayesian network for some values of another node but not all?

Imagine three back to back directed nodes. A -> B -> C Knowing B, A and C are ought to become independant. Imagine B to be binary A & C have positive correlation. After I correct for B, for B=...
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1answer
53 views

Which graph/network format should be used when releasing a data set?

Under RENOIR (an EU funded project) I am working on releasing the data set of Slovenian Press Agency for researchers and other folk. As part of the data set we will be releasing some graphs with ...
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1answer
68 views

Spatial analysis of the network data

I'm a bit new in the spatial statistics (althought I'm not new in statistical analysis, particular in Bayesian inference). When we have point measurements in space - geostatistics/spatial statistics ...
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0answers
87 views

Machine Learning and Flow Maximization

Has anyone ever seen machine learning (ML) used to assist a Max Flow algorithm? I have a very large directed graph that has some fractal characteristics, meaning that this large graph can be roughly ...
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0answers
32 views

State-dependent tandem network of queues

I've been studying network of queues and I would like to model a system by a tandem state-dependent network of queues. I know Jackson network works for $M/M/$ networks, but not for queues where the ...
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1answer
3k views

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 ...
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2answers
177 views

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 ...
4
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1answer
996 views

Degree correlation of network

I'm trying to analyze the degree correlation of a given network and I can't understand what is the best way to do it. With degree correlation I mean to find if the network is assortative (hubs ...
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0answers
17 views

Need to solve a “pseudo-metabolic” network for rates

Sorry about the re-post from Biology section... following problem: I have data on a certain complex association network (from monomers 1 ... 8 to complexes of all combinations, such as, 12 ... 13 ... ...
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0answers
789 views

How to deal with Network Effects in AB Testing?

Say you wanted to AB test a particular treatment on a social network and measure the number of shares. Unfortunately, this is a very naive metric to use because we aren't accounting for the network ...
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0answers
196 views

Nodes placement in knowledge map of Khan Academy

I have been through the Khan Academy blog regarding construction of knowledge map. However after going through it, it left me confused regarding how are they placing the nodes (hierarchically) and ...
3
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1answer
146 views

Social Network Analysis

all: I am new to social network analysis, please pardon if this is a simple question. I am using GEPHI to create a network. My data is a set of ratings by peers in group settings (sociometric). ...
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0answers
28 views

Cluster into communities a graph with negative edge weights representing repulsion [duplicate]

Consider an undirected graph $g$ with some edges having negative weight - all weights in $[-1,1]$. We are seeking communities or clusters. Negative edge weight means repulsion and positive means ...
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1answer
23 views

Method for inferring tree structure from messy sequence data

I have data about case events in criminal cases. These data are in the form of sequence like ...
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1answer
4k views

2SLS with endogenous interaction term

I am trying to estimate a peer effects model where a certain characteristic of the individual and the peers might be endogenous: $$\ y_i=\alpha + \beta_1 Controls_i + \gamma_1 Endog_i +\gamma_2 \...
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4answers
2k views

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 ...
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0answers
747 views

Pagerank vs Eigenvector centrality

What are the practical differences between PageRank and Eigenvector centralities? I don't mean the differents in how to compute the centralities, but the information they provide of a set of nodes in ...
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1answer
404 views

Betweenness values for nodes different in SNAP and iGraph network analysis packages?

I compared results from using the SNAP (Stanford Network Analysis Project) Python library and the iGraph R library for analyzing networks. The betweenness values for nodes seem to be rather different ...