How to get a correlation matrix from a pairwise correlation data.frame?

Question

I have a pairwise correlation dataframe which looks like this (this is just the head) :

      var1                var2  corr
1  OTU3978 UniRef90_A0A010P3Z8 0.846
2  OTU4011 UniRef90_A0A010P3Z8 0.855
3  OTU4929 UniRef90_A0A010P3Z8 0.829
4  OTU4317 UniRef90_A0A011P550 0.850
5  OTU4816 UniRef90_A0A011P550 0.807
6  OTU3902 UniRef90_A0A011QPQ2 0.836
7  OTU3339 UniRef90_A0A011RKI6 0.835
8  OTU1359 UniRef90_A0A011RLA7 0.801
9  OTU2085 UniRef90_A0A011RLA7 0.843
10 OTU3542 UniRef90_A0A011RLA7 0.866

I would like to get the correlation matrix from this dataframe I tried :

library(igraph)
G <- graph.data.frame(df,directed=FALSE)
A <-as_adjacency_matrix(G,names=TRUE,sparse=FALSE,attr="corr",type='lower')

But it didn't work.

Answer 1

There are a few ways to do this. One approach is the acast you mentioned, but you can also use spread from tidyr

library(tidyr)

var1 <- c("A", "B", "C", "D")
var2 <- c("E", "E", "F", "F")
corr <- c(0.2, 0.3, 0.4, 0.5)
df <- data.frame(var1, var2, corr)
df
  var1 var2 corr
1    A    E  0.2
2    B    E  0.3
3    C    F  0.4
4    D    F  0.5
df <- spread(df, var2, corr)
df
  var1   E   F
1    A 0.2  NA
2    B 0.3  NA
3    C  NA 0.4
4    D  NA 0.5