nw2fromedge

Import two-mode network data from edgelist

Syntax

nw2fromedge 
level1
level2
[tievalue]
[if]
[,
nwfromedge_options
]

Description

nw2fromedge imports a two-mode network from a dataset in edgelist format. It is very similar to nwfromedge.

A two-mode network consists of two sets of units (e. g. people and events) and relations connect the two sets, e. g. participation of people in social events. Some examples are:

• Membership in institutions - people, institutions, is a member, e.g. directors and commissioners on the boards of corporations.

• Voting for suggestions - polititians, suggestions, votes for.

• Citation network, where first set consists of authors, the second set consists of articles/papers, connection is a relation author cites a paper.

• Co-autorship networks - authors, papers, is a (co)author. A corresponding graph is called bipartite graph – lines connect only vertices from one to vertices from another set – inside sets there are no connections.

An edgelist is a set of two (or three in the case of a valued network) variables representing relations. Nodes are identified by entries in the cells. For example, the data

• . use “https://raw.githubusercontent.com/thomas-u-grund/nwcommands/master/data/institutions.dta”, clear
• . list _all
• hline 10c -hline 11c -hline 7

• c	person institu~n years c

• hline 10c -hline 11c -hline 7

• 1. c	Thomas Oxford 5 c

• 1. c	Peter Oxford 7 c

• 1. c	Tim Oxford 4 c

• 1. c	Peter LiU 1 c

• 1. c	Tim LiU 1 c

• hline 10c -hline 11c -hline 7

• 1. c	Thomas LiU 1 c

• 1. c	Mathilde UdeM 5 c

• 1. c	Thomas UdeM 1 c

• 1. c	Michael ETH 3 c

• 1. c	Michael Groningen 5 c

• hline 10c -hline 11c -hline 7

• 1. c	Thomas ETH 1 c

• hline 10c -hline 11c -hline 7

stores information about the affiliation of individual researchers.

The following command declares such data as two-mode network data:

. nw2fromedge person institution, name(mynet)

Besides setting the network, this also creates a new variable _nwmode, which has the value 1 for persons (Peter, Tim, Thomas, Michael, Mathilde) and value 2 for institutions (LiU, UdeM, Oxford, ETH, Groningen).

nwplot has no bipartite-specific logic of its own, so nodes are not colored by mode automatically; pass the _nwmode variable this command creates to color() (or symbol()) explicitly to tell the two node sets apart at a glance:

. nwplot mynet, color(_nwmode)

Supported network types

Two-mode: T1, native - this command’s entire purpose is building a two-mode network directly from an edge list (ego/alter columns drawn from two distinct node sets). Binary: yes. Directed: not applicable - two-mode ties are inherently undirected affiliations. Weighted: yes, via a third edge-list column. Signed: not checked. A node with zero ties (an isolate) is never created - an edgelist has no way to record one - use nwaddnodes’s own mode() option afterward to add any isolates the source data could not represent.