Question

I am trying to read multiple files in R from the working directory and would like to read like to read from the 7th row for each file. I am not sure how can i do that

I found how to read an individual file with this:

data = read.csv(file.choose (),  skip = 6 )  

or I can read multiple files like this:

j = list.files()         
     d = lapply(j, read.csv)

could you please help me with how can i read multiple files starting from the 7th row?

Answer 1

In addition to @James’s answer, using lapply only reads the files into a list, not into a common data.frame. From your question it is not obvious if you want this. But I’ll add it for completeness sake anyway.

To be able to identify to which file a row in the common data.frame belonged originally, I often add a column with the filename. In pseudo-code this would look something like:

files = list.files()
data_list = lapply(files, function(f) {
     dat = read.csv(fname, skip = 6)
     dat$fname = fname
     return(dat)
   })
data_df = do.call("rbind", data_list)

Alternatively, you could use the awesome plyr library, which does the exact same thing in:

library(plyr)
files = list.files()
data_df = ldply(files, read.csv, skip = 6)

I have not tested this pseudo-code, so it could be that there are some flaws yet. But you get the basic idea. One problem for example could be that ldply does not automatically adds the filename as a column. Then you need to use the function call as I did using lapply. In that case, ldply saves you the do.call step. Note that plyr supports a progress bar (nice for long processes) and parallel processing.

note:

• I like more descriptive names than j and d. This makes the code easier to read.