nwtoedge

Convert network to edgelist

Syntax

nwtoedge 
[netlist]
[,
egovars(varlist)
altervars(varlist)
ego(newvarname)
alter(newvarname)
comparevars(varlist)
comparemode(mode)]

egovars(varlist)	Keep attributes of sending nodes
altervars(varlist)	Keep attributes of receiving nodes
ego(newvarname)	Sender of ties; default = _ego
alter(newvarname)	Receiver of ties; default = _alter
comparevars(varlist)	Add an ego/alter comparison column for each variable (e.g. same, dist)
comparemode(mode)	Comparison used for comparevars(); default = same
compress	Compress edgelist
full	List both (i,j) and (j,i) for an undirected network’s dyads, rather than only one entry per dyad; forced automatically whenever any network in a netlist is directed
upper	List only one entry per undirected dyad (the default; see full above) - has no effect and is suppressed with a warning on a directed network
numeric	Return every possible node pair (a full node x node grid), not just actual ties; only allowed with a single network
ignore2mode	Treat a two-mode network like a one-mode one - suppress the mode indicator that would otherwise be added to egovars()/altervars() automatically
isolates0	reserved; not currently implemented

Description

nwtoedge makes an edgelist from a network or a list of networks.

An edgelist of a single network netname produced by nwtoedge is a set of three variables representing the relations in the network. The first variable (_ego) gives the nodeid of the sending node i of a relationship; the second variable (_alter) gives the nodeid of the receiving node j. Lastly, the variable netname saves information about the dyad pair (i,j) in the network netname.

When a network is undirected only one entry for the dyad pair (i,j) is generated, unless option full is specified.

When the command is used with a netlist, it generates one new variable for each network netname in the list. If only one of the networks in netlist is directed, the option full is enforced.

One can also include node attributes (saved as normal Stata variables) in the edgelist. Option egovars() generates new variables that match the attributes of the sender of a tie (ego); option altervars() generates new variables that match the attributes of the receiver of a tie (alter).

For example,

. nwwebuse glasgow1

• . nwtoedge glasgow1, egovars(sport1)
• . list
• hline 9c -hline 7c -hline 10c -hline 13

• c	_ego _alter glasgow1 from_sport1 c

• hline 9c -hline 7c -hline 10c -hline 13

• 1. c	1 1 0 regular c

• 1. c	1 2 0 regular c

• 1. c	1 3 0 regular c

• 1. c	1 4 0 regular c

• 1. c	1 5 0 regular c

• hline 9c -hline 7c -hline 10c -hline 13

• 1. c	1 6 0 regular c

• …..
• hline 9c -hline 7c -hline 10c -hline 13

• 1. c	1 11 1 regular c

• 1. c	1 12 0 regular c

• 1. c	1 13 0 regular c

• 1. c	1 14 1 regular c

• 1. c	1 15 0 regular c

• hline 9c -hline 7c -hline 10c -hline 13
• …..

loads the Glasgow data and transforms the network glasgow1 in an edgelist. For example, glasgow1[11] = 1 means, that there is a network tie from node 1 to node 11. It also generates a new variable from_sport1, which holds in this case information about the attribute of the sender of a tie on the original variable sport1.

For two-mode networks see introduction to two-mode networks) and nw2toedge.

The command can also transform two (or more) networks in edgelists at the same time.

. nwtoedge glasgow1 glasgow2

This generates a dataset with one variable for each network, glasgow1 and glasgow2:

• . list
• hline 9c -hline 7c -hline 10c -hline 10

• c	_ego _alter glasgow1 glasgow2 c

• hline 9c -hline 7c -hline 10c -hline 10

• 1. c

     1 1 0 0 c

• 1. c

     1 2 0 0 c

• 1. c

     1 3 0 0 c

• 1. c

     1 4 0 0 c

• 1. c

     1 5 0 0 c

• hline 9c -hline 7c -hline 10c -hline 10

• 1. c

     1 6 0 0 c

• 1. c

     1 7 0 0 c

• 1. c

     1 8 0 0 c

• 1. c

     1 9 0 0 c

• 1. c	1 10 0 1 c

• hline 9c -hline 7c -hline 10c -hline 10

• 1. c	1 11 1 0 c

• 1. c	1 12 0 0 c

• 1. c	1 13 0 0 c

• 1. c	1 14 1 1 c

• 1. c	1 15 0 0 c

• …..

comparevars(varlist) adds an ego/alter comparison column for each listed variable, alongside (not instead of) whatever egovars()/altervars() already add - e.g. “do ego and alter share the same value” or “how far apart are their values”, rather than just the two raw values side by side. comparemode() picks which comparison (any nwexpand mode - same (the default), dist, absdist, distinv, absdistinv, sender, receiver) applies to every variable in comparevars(); each variable is internally expanded via nwexpand itself (so the exact same, already-certified comparison logic is used, not a reimplementation) and the resulting column is named mode_varname - matching nwexpand’s own default naming - e.g. comparevars(sport1) with the default comparemode(same) adds a column named same_sport1. dist/distinv/sender/ receiver comparisons are directional (ego’s value relative to alter’s, not the reverse), so adding one automatically triggers the same “any directed network in the list forces full” rule already used for a mixed directed/undirected netlist - every dyad appears in both directions, so the signed comparison is preserved correctly for both.

. nwwebuse glasgow, nwclear
. nwtoedge glasgow1, comparevars(sport1) comparemode(same)
. nwtoedge glasgow1, comparevars(sport1) comparemode(dist)

Supported network types

Binary: yes. Directed: yes. Weighted: yes, tie values are carried into the edge list. Signed: not checked. Two-mode: yes - see nw2toedge for the two-mode-specific counterpart, though this command’s own egovars()/altervars() two-mode handling is used internally by several other commands directly on a two-mode network too.

When converting a single network, this command also attaches that network’s own full node list to the resulting dataset as a hidden characteristic (no visible extra rows/variables) - purely so a later nwfromedge call on this same edgelist can restore any isolate (zero-tie node) that an edgelist, by construction, cannot represent as a row of its own. See nwfromedge’s own Supported network types section for the other half of this.

See also

• nwfromedge, nw2toedge, nwsave, nwexpand

• last certified : 24 Aug 2026