I have a matrix in R. Each entry i
, j
is a score and the rownames and colnames are ids.
Instead of the matrix I just want a 3 column matrix that has: i
, j
, score
Right now I'm using nested for loops. Like:
for(i in rownames(g))
{
print(which(rownames(g)==i))
for(j in colnames(g))
{
cur.vector<-c(cur.ref, i, j, g[rownames(g) %in% i,colnames(g) %in% j])
rbind(new.file,cur.vector)->new.file
}
}
But thats very inefficient I think...I'm sure there's a better way I'm just not good enough with R yet. Thoughts?
If you convert your matrix first to a table (with as.table
) then to a data frame ( as.data.frame
) then it will accomplish what you are asking for. A simple example:
> tmp <- matrix( 1:12, 3 )
> dimnames(tmp) <- list( letters[1:3], LETTERS[4:7] )
> as.data.frame( as.table( tmp ) )
Var1 Var2 Freq
1 a D 1
2 b D 2
3 c D 3
4 a E 4
5 b E 5
6 c E 6
7 a F 7
8 b F 8
9 c F 9
10 a G 10
11 b G 11
12 c G 12
If I understand you correctly, you need to flatten the matrix.
You can use as.vector
and rep
to add the id columns eg :
m = cbind(c(1,2,3),c(4,5,6),c(7,8,9))
row.names(m) = c('R1','R2','R3')
colnames(m) = c('C1','C2','C3')
d <- data.frame(i=rep(row.names(m),ncol(m)),
j=rep(colnames(m),each=nrow(m)),
score=as.vector(m))
Result:
> m
C1 C2 C3
R1 1 4 7
R2 2 5 8
R3 3 6 9
> d
i j score
1 R1 C1 1
2 R2 C1 2
3 R3 C1 3
4 R1 C2 4
5 R2 C2 5
6 R3 C2 6
7 R1 C3 7
8 R2 C3 8
9 R3 C3 9
Please, note that this code converts a matrix into a data.frame
, since the row and col names can be string and you can't have a matrix with different column type.
If you are sure that all row and col names are numbers, you can coerced it to a matrix.
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