[R] Reading multiple csv files

Madhavi Bhave
Fri, 26 Feb 2010 08:15:07 -0000

Dear R helpers

Some particular analysis leads me to various number of output csv files
depending on some conditions. Say e.g. I have output files variable1.csv,
variable2.csv, .............. Problem is I don't know how many csv files
been generated. They could be 4, 5 or even 10. Each file will have a column
called amount.

My problem is to find filewise mean(amount) and sd(amount). I need to write a
loop where all these individual csv files will be read and after reading each
file, mean and sd will be calculated.

I have tried to write some R code which is very absurd.

for (i in 1 : n)  # n is no of input files

{
data[i] = read.csv(file = paste("variable", i, ".csv", sep =
""))$amount
mean(data[i])
sd(data[i])
}

I get following error.

Error in file(file, "rt") : cannot open the connection
In addition: Warning message:
In file(file, "rt") :
  cannot open file 'paste("output", i, ".csv", sep =
"")': Invalid argument


Please guide

Regards

Madhavi


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