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Re: st: convert adjacency to edgelist


From   Mike Lacy <Michael.Lacy@colostate.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: convert adjacency to edgelist
Date   Sat, 14 Feb 2009 10:35:15 -0700


>
>Date: Fri, 13 Feb 2009 16:25:36 -0500
>From: "Victor, Jennifer Nicoll" <jnvictor@pitt.edu>
>Subject: st: convert adjacency to edgelist
>
>Hello Stata users,
>
>I have a 438x438 adjacency matrix (symmetrical, non-directed) where
>the cells are the number of connections between each i,j pair (the
>pairs are members of congress and the connections are the number of
>caucuses each pair is in).  I have it in Excel format, csv format, and
>Stata format.  I also have it in Stata as a dyadic dataset with
>attribute variables (N=95,703).   I want to convert either the dyadic
>data or the adjacency matrix to an edgelist that I could import into R
>(igraph) or NodeXL or TouchGraph so that I can make a network graph or
>two, but I need an edgelist to import into those programs.

Can you clarify what you want here with a small example? To go from an adjacency matrix to what I would call an edge list is just a -reshape- from wide to long, which I'm presuming is not what you want.
(i.e, given a Stata data set of the form:    (non-proportional font on)

 +------------------------------+
     | egoid x1   x2   x3   x4   x5 |
     |------------------------------|
  1. |   1    .    2    2    0    1 |
  2. |   2    .    .    0    3    3 |
  3. |   3    .    .    .    2    2 |
  4. |   4    .    .    .    .    2 |
  5. |   5    .    .    .    .    . |
     +------------------------------+
(where x_i is the number of connnections from egoid to i)

Then
reshape long x, i(ego) j(alter)
drop if missing(x)

would yield what I would call an edge list in Stata.
     +-----------------+
     | ego   alter   x |
     |-----------------|
  1. |   1       2   2 |
  2. |   1       3   2 |
  3. |   1       4   0 |
  4. |   1       5   1 |
  5. |   2       3   0 |
     |-----------------|
  6. |   2       4   3 |
  7. |   2       5   3 |
  8. |   3       4   2 |
  9. |   3       5   2 |
 10. |   4       5   2 |
     +-----------------+

Regards,




=-=-=-=-=-=-=-=-=-=-=-=-=
Mike Lacy
Fort Collins CO USA
(970) 491-6721 office






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