CODEWITHSUNDEEP
rcsv
eelie_
eelie_

Reputation: 1

How do I list the number of rows for a lot of x number of csv files?

I've been trying to figure out a way to get the number of rows for a certain number of CSVs. I can get R to output the number of rows (minus the NAs) for one file.

But when I try to use the Colon Operator I keep getting an error:

Error in file(file, "rt") : invalid 'description' argument

The auction I created:

complete <- function(directory,id = 1:332){
  ## 'directory is a character vector of length 1 indicating
  ## the location of the CSV files

  ## 'id' is an intiger vector indicating the monitor ID numbers
  ## to be used

  ## Return a data frame of the form:
  ## id nobs
  ## 1  117
  ## 2  1041
  ## ...
  ## where 'id' is the monitor ID and 'nobs' is the
  ## number of complete cases

  filenames <- sprintf("%03d.csv", id)
  filenames <- paste(directory, filenames, sep="/")

  file1 <- read.csv(filenames)

  n_row <- NROW(na.omit(file1))

  output <- data.frame(id,nobs=n_row)

  output
}

I tried using a for loop to loop read each file:

  for (i in id){
    filenames <- sprintf("%03d.csv", id)
    filenames <- paste(directory, filenames, sep="/")

    file1 <- read.csv(filenames)

    n_row <- NROW(na.omit(file1))

    output <- data.frame(id,nobs=n_row)  
  }
  output

That still comes up with the Error:

 Error in file(file, "rt") : invalid 'description' argument

Any hints on where I can go from here?

Thanks

Upvotes: 0

Views: 60

Answers (2)

eipi10
eipi10

Reputation: 93761

If you have a vector filenames containing path to each file, then something like this should work: 

fl = sapply(filenames, function(x) {
  dat = read.csv(x)
  return(data.frame(file=x, nobs=nrow(na.omit(dat))))
}, simplify=FALSE)

do.call(rbind, fl)

Upvotes: 1

Sijo Jose
Sijo Jose

Reputation: 41

if your files are named as 1.csv,2.csv,3.csv.

id=1:4
df=NULL
for (i in 1:length(id)) {
  n_row<-NROW(na.omit(read.csv(paste0("C:/Users/fol/",id[i],".csv"))))  
  df=rbind(df,data.frame(id=id[i],nobs=n_row))
}

Upvotes: 0

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