export - Exporting an R Spread Table

Question

I'm new to R, but have had some initial success grabbing data (gwlevel) and then using the "spread function" to put into a spread table (gwlevel_spread).

My problem is that I can easily export the "gwlevel" table, as follows:

write.table(gwlevel, file = "c:/BOB/r/export/zz_jnk.csv")

However, I keep getting an error when I try to export the "gwlevel_spread" file, as follows:

write.table(gwlevel_spread,"c:/BOB/r/export/zz_jnk.csv",sep=",") Error in write.table(gwlevel_spread, "c:/BOB/r/export/zz_jnk.csv", sep = ",") : unimplemented type 'list' in 'EncodeElement'

(1) Can anybody tell me the reason? (2) Or is there a better way I should be doing it?

Answer 1

That probably means that you have some list columns in your data which cannot be exported to csv. You can collapse the list column to one comma-separated string before writing it to csv.

If the list column is called col you can do :

gwlevel_spread$col <- sapply(gwlevel_spread$col, toString)

If you don't know which column is list or have many columns that are of list class in your data you can use condition in lapply

gwlevel_spread[] <- lapply(gwlevel_spread, function(x) 
                          if('list' %in% class(x)) sapply(x, toString) else x)

and then write to csv using write.table or write.csv :

write.table(gwlevel_spread, file = "c:/BOB/r/export/zz_jnk.csv")