Apply a function returning a data frame to each row in a data frame

Question

I have a data frame d and a function f that takes each row of the data frame to return a data frame:

d <- data.frame(x=c(1,2,3),y=c(11,22,33))

f <- function(row){
...
return(df)
}

Now, I want to apply f to d (to avoid looping through f(d[k,] of course). apply can´t work and putting the rows of d in a list and using lapply failed. What should I do?

Does this answer your question? [R: apply-like function that returns a data frame?](https://stackoverflow.com/questions/36982755/r-apply-like-function-that-returns-a-data-frame) — caldwellst, Aug 12 '20 at 09:53
`apply(d, 1, f)` doesn't work? How about `lapply(asplit(d, 1), f)` ? — Ronak Shah, Aug 12 '20 at 10:02
@RonakShah No, I get "$ operator is invalid for atomic vectors" despite `f` working fine for all rows (`d[k,]`) seperately — Claudio Moneo, Aug 12 '20 at 10:07

score 1 · Accepted Answer · answered Aug 12 '20 at 10:10

You haven't shown what you have in f but based on comments it is written for dataframes, so this should work :

lapply(split(d, seq_len(nrow(d))), f)

split divides every row of d in 1 row-dataframe and using lapply we apply function f on each row.

You can also use by :

by(d, seq_len(nrow(d)), f)

Apply a function returning a data frame to each row in a data frame

1 Answers1