how to get the frequency of unique elements in a column of a dataframe in R?

Question

I have a dataframe:

 X65L X65L.1 X65L.2   X67L X67L.1 X65L.3
 [1,] 0.0065 0.0065 0.0065 0.0067 0.0067 0.0065
 [2,] 0.0065 0.0065 0.0065 0.0067 0.0067 0.0065
 [3,] 0.0065 0.0065 0.0065 0.0067 0.0067 0.0065
 [4,] 0.0065 0.0067 0.0065 0.0067 0.0067 0.0065
 [5,] 0.0065 0.0067 0.0065 0.0067 0.0067 0.0065
 [6,] 0.0065 0.0067 0.0065 0.0067 0.0067 0.0065
 [7,] 0.0067 0.0071 0.0067 0.0067 0.0071 0.0067
 [8,] 0.0067 0.0071 0.0067 0.0067 0.0071 0.0067
 [9,] 0.0067 0.0071 0.0067 0.0067 0.0071 0.0071
[10,] 0.0067 0.0084 0.0067 0.0067 0.0084 0.0071
[11,] 0.0067 0.0084 0.0067 0.0067 0.0084 0.0084
[12,] 0.0067 0.0084 0.0067 0.0067 0.0084 0.0084

I want to count the frequency of each unique element in a column and get an output like this:

     6     3     6     0     0     6
     6     3     6    12     6     2
     0     3     0     0     3     2
     0     3     0     0     3     2

The MATLAB equivalent is:

[m1 n1]=hist(s,unique(s));

I would like to know, how this could be done in R.

Answer 1

You can try the code below

apply(mat, 2, function(x) table(factor(x, levels = unique(c(mat)))))

which gives

       X65L X65L.1 X65L.2 X67L X67L.1 X65L.3
0.0065    6      3      6    0      0      6
0.0067    6      3      6   12      6      2
0.0071    0      3      0    0      3      2
0.0084    0      3      0    0      3      2

Data

> dput(mat)
structure(c(0.0065, 0.0065, 0.0065, 0.0065, 0.0065, 0.0065, 0.0067, 
0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0065, 0.0065, 0.0065,
0.0067, 0.0067, 0.0067, 0.0071, 0.0071, 0.0071, 0.0084, 0.0084,
0.0084, 0.0065, 0.0065, 0.0065, 0.0065, 0.0065, 0.0065, 0.0067,
0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 
0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067,
0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0067, 0.0071,
0.0071, 0.0071, 0.0084, 0.0084, 0.0084, 0.0065, 0.0065, 0.0065,
0.0065, 0.0065, 0.0065, 0.0067, 0.0067, 0.0071, 0.0071, 0.0084,
0.0084), .Dim = c(12L, 6L), .Dimnames = list(NULL, c("X65L",
"X65L.1", "X65L.2", "X67L", "X67L.1", "X65L.3")))