Question

I have data in a matrix in the following way:

label     1        2      3       4
id_101   10       30      43      32
id_102    3       32     43       43
id_111    45      34     22       66
id_201    87      65     66       34
id_202    45      76     76       44
......

this data has been transformed in a list so it is like:

[[1]]
     [1]  label   1     2       
     [3]      3   4
[[2]]
     [1]  id_101 .....

 ......

what I want is to know if a value a matches one of the values from the column named label. For that purpose I am using a for loop with the match instruction:

    a<-"id_201"    ///for example
for (pos in 2:length(matrix))
{

    if (!is.na(match(a,tabd[[pos]][[1]])))
    {
        found<-1
        print(found)
        break
    }
}
    if (found) print(pos)

I was wondering if there is an efficient way to look if the value from the variable a matches any value of the column under label and to get its position, but without using the for loop.
Thanks

Answer 1

I have made a list somewhat like what you describe, although it prints with surounding double quotes. Working with it suggests this should work

which( sapply(txtList, "[", 1) == a )