Question

Working through an R tutorial that I’m having a hard time understanding.

Directory is a folder with numerous csv files. The function takes as id either one of more of the files and returns the number of records in each.

My function:

complete <- function(directory,id = 1:332) {

   csvfiles <- sprintf("/Users/myname/Desktop/%s/%03d.csv", directory, id)

   nrows <- sapply( csvfiles, function(f) nrow(read.csv(f)))
   data.frame(ID=sprintf('%03d', id), 
              countrows=sapply(csvfiles,function(x) length(count.fields(x))),
             row.names=id
           )
       }

Then complete(“specdata”, 100:105)
Returns

    ID countrows
100 100      1097
101 101       731
102 102      1462
103 103      3653
104 104      2558
105 105      2192

What must I do so that the left most column is a sequence starting 1? So that, for example, the first record would be 1 100 & 1092, the second record 2 101 & 731

Answer 1

The first apparent column is just the names of the rows (look at e.g. ncol(specdata)). You can rename rows as follows:

row.names(specdata) <- 1:nrow(specdata)