Unimplemented type list when trying to write.table

Question

I have the following data.table (data.frame) called output:

> head(output)
        Id                                           Title IsProhibited
1 10000074                             Renault Logan, 2005            0
2 10000124              Ñêëàäñêîå ïîìåùåíèå, 345 ì<U+00B2>            0
3 10000175                                          Ñó-øåô            0
4 10000196             3-ê êâàðòèðà, 64 ì<U+00B2>, 3/5 ýò.            0
5 10000387        Samsung galaxy S4 mini GT-I9190 (÷¸ðíûé)            0
6 10000395 Êàðòèíà ""Êðûì. Ïîñåëîê Àðîìàò"" (õîëñò, ìàñëî)            0

I am trying to export it to a CSV like so:

> write.table(output, 'output.csv', sep = ',', row.names = FALSE, append = T)

However, when doing so I get the following error:

Error in .External2(C_writetable, x, file, nrow(x), p, rnames, sep, eol,  : 
unimplemented type 'list' in 'EncodeElement'
In addition: Warning message:
In write.table(output, "output.csv", sep = ",", row.names = FALSE,  :
  appending column names to file

I have tried converting the Title to a string so that it is no longer of type list like so:

toString(output$Title)

But, I get the same error. My types are:

> class(output)
[1] "data.frame"
> class(output$Id)
[1] "integer"
> class(output$Title)
[1] "list"
> class(output$IsProhibited)
[1] "factor"

Can anyone tell me how I can export my data.frame to CSV?

Another strange thing that I've noticed, is that if I write head(output) my text is not encoded properly (as shown above) whereas if I simply write output$Title[0:3] it will display the text correctly like so:

> output$Title[0:3]
[[1]]
[1] "Renault Logan, 2005"

[[2]]
[1] "Складское помещение, 345 м²"

[[3]]
[1] "Су-шеф"

Any ideas regarding that? Is it relevant to my initial problem?

Edit: Here is my new output:

Id  Title   IsProhibited    
10000074    Renault Logan, 2005 0   
10000124    СкладÑкое помещение, 345 м<U+00B2>    0   
10000175    Су-шеф 0   
10000196    3-к квартира, 64 м<U+00B2>, 3/5 ÑÑ‚.  0   
10000387    Samsung galaxy S4 mini GT-I9190 (чёрный)  0   
10000395    Картина \\"Крым. ПоÑелок Ðромат\"\" (холÑÑ‚     маÑло)"    0
10000594    КальÑн 25 Ñм  0   
10000612    1-к квартира, 45 м<U+00B2>, 6/17 ÑÑ‚. 0   
10000816    Гараж, 18 м<U+00B2>   0   
10000831    Платье    0   
10000930    Карбюраторы К-22И, К-22Г от газ 21 и газ 51 0   

Notice how line ID 10000395 is messed up? It seems to contains quotes of it's own which are messing up the CSV. How can I fix that?

Answer 1

Do this, irrespective of how many columns you have:

df <- apply(df,2,as.character)

Then do write.csv.

Answer 2

As mentioned in the comments, you should be able to do something like this (untested) to get "flatten" your list into a character vector:

output$Title <- vapply(output$Title, paste, collapse = ", ", character(1L))

As also mentioned, if you wanted to try the unlist approach, you could "expand" each row by the individual values in output$Title, something like this:

x <- vapply(output$Title, length, 1L)          ## How many items per list element
output <- output[rep(rownames(output), x), ]   ## Expand the data frame
output$Title <- unlist(output$Title, use.names = FALSE)  ## Replace with raw values

Answer 3

There is a new function (introduced in november 2016) in data.table package that handles writing a data.table object to csv quite well, even in those cases when a column of the data.table is a list.

fwrite(data.table, file ="myDT.csv")