[R] factor manipulation: edgelist to a matrix?

From: Christopher Marcum <cmarcum_at_uci.edu>
Date: Wed, 19 Dec 2007 23:33:15 -0800 (PST)

Hello All,

I have had considerable bad luck with attempting the following with for loops. Here is the problem:

# Suppose we have a data.frame with the following data, which can be
considered a type of edgelist (for those with networks backgrounds):
# V1 V2
# 1 A
# 1 A
# 1 B
# 2 A
# 3 C
# 3 A
# 3 C
# 3 B
# I want the output of the function to produce a matrix, such that #each
factor of V1 is a row, and each corresponding value at position k of V2 is the i,j^th element of the new matrix, with missing values otherwise. The desired output should be:
# [,1] [,2] [,3] [,4]
# [1,] A A B NA
# [2,] A NA NA NA
# [3,] C A C B

I have explored the reshape package as well as the network package in this pursuit, with no luck.

Chris Marcum
UCI Sociology

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