CODEWITHSUNDEEP
rmergerbindcbind
NoobMat
NoobMat

Reputation: 103

Merge and Sum Multiple CSV files in R

First Question/Post, Hopefully I've not duplicated this but have searched as many terms as I can think of. I'm sure this is going to be a "doh" moment, But here goes:

Using R I'm trying to read in several 100 .csv files, of two columns each, type and time elapsed, eg:

Col1    Col2
Type A  11:20:15
Type B  29:40:34
Type C  45:13:26

I'm trying to merge every file in the folder to produce a single DF with a sum of all the times, but I'm drawing a blank really appreciate any guidance to right functions to look at or solutions

Here's Where I'm at:

    files = list.files(pattern="*.csv")
    fileno <- length(files)

    for (i in 1:fileno){
    assign(files[i], read.csv(files[i]))
    ###Code to Read each "time" and Sum with current
    # TotalDF <- Time Value from Current loaded CSV "Summed" to TotalDF
    }

If I had two files:

Col1    Col2
Type A  11:20:15
Type B  29:40:34
Type C  45:13:26

Col1    Col2
Type A  5:00:00
Type B  3:00:00
Type C  8:00:00

Then TotalDF would be:

Col1    Col2
Type A  16:20:15
Type B  32:40:34
Type C  53:13:26

Upvotes: 1

Views: 1986

Answers (1)

Michele Usuelli
Michele Usuelli

Reputation: 2000

You can load all of them into a list and use Reduce.

# define a vector with the file paths
nameFolder <- "data"
vectorFiles <- list.files(nameFolder, full.names = TRUE)

# load each file and change the name of the second column
listDf <- lapply(vectorFiles, function(fileName){
  dfFile <- read.csv(fileName)
  names(dfFile)[2] <- fileName
  return(dfFile)
})

# merge the data frames on the column Col1
dfMerged <- Reduce(function(...) merge(..., by = "Col1"), listDf)

Upvotes: 2

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