Export multiple data frames into .csv files using R

user_3887476 0
Viewed 460

I would like to export several dataframes as separate csv files to the working directory with a loop rather than writing out all of th names

##Sample data frame

employee <- c('John Doe','Peter Gynn','Jolie Hope')
salary <- c(21000, 23400, 26800)
startdate <- as.Date(c('2010-11-1','2008-3-25','2007-3-14'))
d30 <- data.frame(employee, salary, startdate)

##Creating a few of the same name for illustrative purposes
d39 <- data.frame(employee, salary, startdate)
d40 <- data.frame(employee, salary, startdate)

for (list in c(d30,d39)){
  write.csv(list, file="list.csv", row.names = FALSE)
}

Obviously I'm quite wrong. But I can't figure out how to do it.

r loops
3 Answers

Iterate over the data frame names. We assume all names start with d and are of length 3. Modify the pattern if not or directly set nms if you know them. We also make a second check that the names are data frames but you can omit that check if you are sure that there are no objects that are not data frames and have a name matching the pattern.

nms <- ls(pattern = "^d..$")
for(nm in nms) {
  X <- get(nm)
  if (is.data.frame(X)) {
    filename <- paste0(nm, ".csv")
    message("writing out ", filename)
    write.csv(X, file = filename, row.names = FALSE)
  }
}
user_5165480 
i <- 1

dfs <- list(d30, d39)

for (df in dfs){
  filename <- paste0("list", " ", i, ".csv")
  write.csv(list, file=filename, row.names = FALSE)
  i <- i + 1
}
user_97789460

Data

employee <- c('John Doe','Peter Gynn','Jolie Hope')
salary <- c(21000, 23400, 26800)
startdate <- as.Date(c('2010-11-1','2008-3-25','2007-3-14'))

Code: 

# create a new environment
myenv <- new.env()
# create data frames inside the environment
myenv$d30 <- data.frame(employee, salary, startdate)
myenv$d40 <- data.frame(employee, salary, startdate)

# get data from environment and write to files.
for (list in mget(ls(envir = myenv), envir = myenv)){
  write.csv(list, file="list.csv", row.names = FALSE)
}
user_16917230
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