Extracting nth element from a nested list following strsplit - R

Question

I\'ve been trying to understand how to deal with the output of strsplit a bit better. I often have data such as this that I wish to split:

myd         


        

Answer 1

Try this:

> read.table(text = mydata, sep = "/", as.is = TRUE, fill = TRUE)
   V1 V2 V3
1 144  4  5
2 154  2 NA
3 146  3  5
4 142 NA NA
5 143  4 NA
6 DNB NA NA
7  90 NA NA

If you want to treat DNB as an NA then add the argument na.strings="DNB" .

If you really want to use strsplit then try this:

> do.call(rbind, lapply(strsplit(mydata, "/"), function(x) head(c(x,NA,NA), 3)))
     [,1]  [,2] [,3]
[1,] "144" "4"  "5" 
[2,] "154" "2"  NA  
[3,] "146" "3"  "5" 
[4,] "142" NA   NA  
[5,] "143" "4"  NA  
[6,] "DNB" NA   NA  
[7,] "90"  NA   NA  

Note: Using alexis_laz's observation that x[i] returns NA if i is not in 1:length(x) the last line of code above could be simplified to:

t(sapply(strsplit(mydata, "/"), "[", 1:3))