Counting values in list and creating new colums containing counts-CodePudding

I have a list that of values that I would like to count the first column of each element and create a new dataframe with the counts.

Here is an example:

List:

my_list <- list(cbind(c("a", "b", "a"),c("R", "B", "R")),
                cbind(),
                cbind(c("a", "a", "c","b"),c("B", "R", "R","B")))


> my_list
[[1]]
     [,1] [,2]
[1,] "a"  "R" 
[2,] "b"  "B" 
[3,] "a"  "R" 

[[2]]
NULL

[[3]]
     [,1] [,2]
[1,] "a"  "B" 
[2,] "a"  "R" 
[3,] "c"  "R" 
[4,] "b"  "B"

Desired Output in a dataframe:

     "a"      "b"      "c"
[1,]  2        1        0
[2,]  0        0        0
[3,]  2        1        1

CodePudding user response：

Convert the list elements to factor with levels specified as 'a', 'b', 'c' and get the frequency count with table

t(sapply(my_list, \(x) table(factor(x, levels = c("a", "b", "c")))))
     a b c
[1,] 2 1 0
[2,] 0 0 0
[3,] 2 1 1