Returning a table of column names by row identity-CodePudding

I've been trying to wrap my head around this one... I have a table of gene expression values that are greater than a certain value, so each is a conditional value (TRUE/FALSE). I want to, for each row, return the column names for the cells that are TRUE. Afterwards, I want a table with the row numbers as column headers, and the column names for TRUE cells in each column. Or alternatively, just a list of 'TRUE' column names for each row number

My input:

> sc_mydata > 0.5
     Slc6a14 / 1420504_at Calca / 1452004_at Ms4a4d / 1418990_at Hsd17b14 / 1429802_at 1432227_at
[1,]                FALSE              FALSE               FALSE                  TRUE       TRUE
[2,]                FALSE               TRUE               FALSE                 FALSE       TRUE
[3,]                FALSE              FALSE               FALSE                 FALSE      FALSE
[4,]                 TRUE              FALSE                TRUE                 FALSE      FALSE

I tried to use a for loop, but it doesn't give me any column names unfortunately. Anyone able to help...?!

CodePudding user response：

How about this:

mat <- matrix(c(FALSE,              FALSE,               FALSE,                  TRUE,       TRUE,
               FALSE,               TRUE,               FALSE,                 FALSE,       TRUE,
               FALSE,              FALSE,               FALSE,                 FALSE,      FALSE,
                TRUE,              FALSE,                TRUE,                 FALSE,      FALSE), 
              ncol=5)
colnames(mat) <- c("Slc6a14 / 1420504_at", "Calca / 1452004_at", "Ms4a4d / 1418990_at",  "Hsd17b14 / 1429802_at",  "1432227_at")

apply(mat, 1, function(x)colnames(mat)[which(x)])
#> [[1]]
#> [1] "Calca / 1452004_at"
#> 
#> [[2]]
#> [1] "Ms4a4d / 1418990_at" "1432227_at"         
#> 
#> [[3]]
#> [1] "Calca / 1452004_at"
#> 
#> [[4]]
#> [1] "Slc6a14 / 1420504_at"  "Hsd17b14 / 1429802_at"

^{Created on 2022-11-24 by the reprex package (v2.0.1)}