r - Calculate the mean of one column across multiple .csv files How? -

i newbie in r , have got calculate mean of column sulf 332 files. mean formulas bellow works 1 file . problem comes when attempt calculate across files.

perhaps reading files , storing them in mydata not work well? me out?

many thanks

pollutantmean <- function(specdata,pollutant=xor(sulf,nit),i=1:332){             specdata<-getwd()             pollutant<-c(sulf,nit)              for(i in 1:332){                mydata<-read.csv(file_list[i])             }               sulfate <- (subset(mydata,select=c("sulfate")))             sulf <- sulfate[!is.na(sulfate)]             y <- mean(sulf)          print(y)         } 

this not tested, steps followed. note kind of questions being asked on , on again (e.g. here). try searching "work on multiple files", "batch processing", "import many files" or akin this.

lx <- list.files(pattern = ".csv", full.names = true)  # gives list of  xy <- sapply(lx, fun = function(x) {   out <- read.csv(x)   out <- out[, "sulfate", drop = false] # not drop vector fun   out <- out[is.na(out[, "sulfate"]), ]   out   }, simplify = false)  xy <- do.call(rbind, xy) # combine result files 1 big data.frame mean(xy[, "sulfate"]) # calculate mean # or summary(xy) 

if short on ram, can optimized bit.