Dataframe within dataframe?

Question

Consider this example:

df <- data.frame(id=1:10,var1=LETTERS[1:10],var2=LETTERS[6:15])

fun.split <- function(x) tolower(as.character(x))
df$new.letter         


        

Answer 1

@akrun solved 90% of my problem. But I had data.frames buried within data.frames, buried within data.frames and so on, without knowing the depth to which this was happening.

In this case, I thought sharing my recursive solution might be helpful to others searching this thread as I was:

    unnest_dataframes <- function(x) {

        y <- do.call(data.frame, x)

        if("data.frame" %in% sapply(y, class)) unnest_dataframes(y)

        y

    }

    new_data <- unnest_dataframes(df)

Although this itself sometimes has problems and it can be helpful to separate all columns of class "data.frame" from the original data set then cbind() it back together like so:

  # Find all columns that are data.frame
  # Assuming your data frame is stored in variable 'y'
  data.frame.cols <- unname(sapply(y, function(x) class(x) == "data.frame"))
  z <- y[, !data.frame.cols]

  # All columns of class "data.frame"
  dfs <- y[, data.frame.cols]

  # Recursively unnest each of these columns
  unnest_dataframes <- function(x) {
    y <- do.call(data.frame, x)
    if("data.frame" %in% sapply(y, class)) {
        unnest_dataframes(y)
    } else {
        cat('Nested data.frames successfully unpacked\n')
      }
    y
  }

  df2 <- unnest_dataframes(dfs)

  # Combine with original data
  all_columns <- cbind(z, df2)