[R] Printing row and column names of cells with specific value in a big matrix

[gaurav kandoi]

Hi All

I've two big matrices (5k*4k) with the same structure, i.e. :

  mRNA1 mRNA2 mRNA3  lncRNA1 0.395646 0.94995 0.76177  lncRNA2 0.03791
0.661258 0.558658  lncRNA3 0.67846 0.652364 0.359054  lncRNA4 0.57769 0.003
0.459127
Now, I would like to extract the names of the row,col pairs whose value is
less than 0.05. In this case, I should get the output as (lncRNA2,mRNA1)
and (lncRNA4,mRNA2) alongwith their values (0.03791 and 0.003). Since the
structure of both the matrix is same, I would also like to retrieve the
corresponding values and row,col names from the second matrix.
(lncRNA2,mRNA1 and lncRNA4,mRNA2 alongwith their values in the second
matrix.)

I'm using the following code:

Pmatrix = read.table("pmatrix.csv", header=T, sep="," , row.names=1)
> sig_values <- which(Pmatrix<0.05, arr.ind=TRUE)
> sig_values
> Corr_Matrix = read.csv("corr_matrix.csv", header = T, row.names=1)
> Corr_Matrix[sig_values]


However, it only prints the row,col number (sig_values command) or only the
values (Corr_Matrix[sig_values]) command. How can I get the row and column
names alongwith their values?

Regards

-- 
*Gaurav Kandoi*

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