Write to files in R using a loop

问题

I have several variables as follow:

cats <- "some long text with info"
dogs <- "some long text with info"
fish <- "some long text with info"
....

and I manually write the content of these variables into a text file:

write.table(cats, "info/cats.txt", sep="\t")
write.table(dogs, "info/dogs.txt", sep="\t")
....

I read the answer to this question and tried to write a loop to automatically write the files.

So I created a list:

lst <<- list(cats, dogs,fish, ....)

and then iterated through the list:

for(i in seq_along(lst)) {
    write.table(lst[[i]], paste(names(lst)[i], ".txt", sep = ""), 
               col.names = FALSE, row.names = FALSE,  sep = "\t")
}

but the output of the above iteration is one text file called .txt and it contains the content of the last variable in the list.

any idea why the above loop doesn't work as expected?

回答1:

Note the following:

> cats <- "some long text with info"
> dogs <- "some long text with info"
> fish <- "some long text with info"
> lst <- list(cats, dogs,fish)  # not <<-
> names(lst)
NULL

When you created your list, you didn't give it any names, so your loop doesn't have anything to work with. A fix:

> names(lst) <- c("cats", "dogs", "fish")

来源：https://stackoverflow.com/questions/35876929/write-to-files-in-r-using-a-loop