How to turn a weighted edgelist into an adjacency matrix in r

Question

I have a weighted edge list and I want to convert it into an adjacency matrix. Is there a simple code I can use to do this?

The data looks like this:

  From To    Weight
1    a  a 0.3274570
2    b  a 0.7188648
3    a  b 0.1097450
4    b  b 0.9054419

Here is replication code:

edgelist <- setNames(cbind(expand.grid(letters[1:2], letters[1:2]), runif(4)), c("From", "To", "Weight"))
edgelist

Answer 1

One approach is to use get.adjacency from the igraph package.

library(igraph)
mygraph <- graph.data.frame(edgelist)
get.adjacency(mygraph, sparse = FALSE, attr='Weight')
#          a         b
#a 0.3274570 0.1097450
#b 0.7188648 0.9054419

While it is certainly possible to simply transform the data to a matrix, it might be helpful to be prepared to use the rest of this package's features.

Answer 2

as.matrix(tidyr::spread(edgelist, "To", "Weight")[-1])