R store the for loop output in vector

Question

I am R beginner, the following is my code:

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


# Read through all the csv data file
for (i in id) {
    i <- sprintf("%03d", as.numeric(i))
    data <- read.csv(paste(directory, "/", i, ".csv", sep =""))
    good <- complete.cases(data)   # Eliminating the NA rows
    cases <- sum(good == TRUE)  # add complete value    
} 


data.frame(id = id, nobs = cases )
}

when I print the output

 id nobs
1  1  402
2  2  402
3  3  402
4  4  402
5  5  402          (incorrect)

if I just print the cases

[1] 117
[1] 1041
[1] 243
[1] 474
[1] 402

so the correct output should be

I realize it only take last value from the (cases).

My question is how can I store the (cases) output into a vector so when I call the data.frame function it will return the correct output.

thanks

EDi · Accepted Answer · 2014-01-17 10:42:57Z

1

This should do the job, if id is a numeric vector (untested since you provided no reprodicible example!)

Otherwise you should use for(i in seq_along(id)) and id[i] inside the loop.

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

cases <- NULL
# Read through all the csv data file
for (i in id) {
    i <- sprintf("%03d", as.numeric(i))
    data <- read.csv(paste(directory, "/", i, ".csv", sep =""))
    good <- complete.cases(data)   # Eliminating the NA rows
    cases[i] <- sum(good == TRUE)  # add complete value    
} 


data.frame(id = id, nobs = cases )
}

answered Jan 17, 2014 at 10:42

EDi

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2 Comments

user1804925 Over a year ago

Thanks, Can you explain what "NULL" do?

EDi Over a year ago

It creates an object cases in your workspace, which it actually empty. In the for loop this object 'grows' to a vector. I must agree with @Sven Hohenstein, that this is not a very efficient solutution, however I wanted to keep the code similare to the one in your question.

Sven Hohenstein · Accepted Answer · 2014-01-17 11:53:14Z

1

This is a more efficient function for the task:

complete <- function(directory, id = 1:332) {
  filenames <- file.path(directory, paste0(sprintf("%03d", id), ".csv"))
  data.frame(id = id, 
             nobs = sapply(filenames, function(x) 
                                        sum(complete.cases(read.csv(x)))))
}

answered Jan 17, 2014 at 11:53

Sven Hohenstein

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Comments

oliver · Accepted Answer · 2017-06-05 07:51:45Z

0

complete <- function(directory ,id = 1:332){
  folder = directory
  df_total = data.frame()
  for (x in id){
    filenames <- sprintf("%03d.csv", x) 
    filenames <- paste(folder,filenames,sep="\\")
    df <- do.call(rbind,lapply(filenames,read.csv, header=TRUE))
    my_vector <- sum(complete.cases(enter the column for which you want))
    df1 <- data.frame(id=x,nobs=my_vector)
    df_total <- rbind(df_total,df1)
  }
  df_total
}

answered Jun 5, 2017 at 7:51

oliver

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