ichbinangela ichbinangela - 3 months ago 22
R Question

Write a data frame containing a list to csv file

I would like to save my data

train.user
(213451 obs. of 20 variables. 2 of the variables are lists) as a csv file.

I use:

write.csv(train.user, "train_user.csv", row.names = FALSE)


but an error occurs

Error in .External2(C_writetable, x, file, nrow(x), p, rnames, sep, eol, :
unimplemented type 'list' in 'EncodeElement'


This is how my data
train.user
looks like. (by using
str
) (showing only part of it)

'data.frame': 213451 obs. of 20 variables:
$ id : Factor w/ 213451 levels "00023iyk9l","0005ytdols",..: 100523 48039 26485 68504 48956 147281 129610 2144 59779 40826 ...
$ gender : Factor w/ 4 levels "-unknown-","FEMALE",..: 1 3 2 2 1 1 2 2 2 1 ...
$ age :List of 213451
..$ : num NA
..$ : num 38
..$ : num 56
..$ : num 42
..$ : num 41
.. [list output truncated]


It seems like the column
age
is stored as a list, and
write.csv
doesn't accept this format. From my naive intuition, I tried to re-store the column as a data frame with following code, but it failed.

train.user$age <- as.data.frame(train.user$age)


Error message:

Error in `$<-.data.frame`(`*tmp*`, "age", value = list(NA_real_. = NA_real_, :
replacement has 1 row, data has 213451


I also tried
train.user$age <- data.frame(lapply(train.user$age, unlist))
as suggested in another post, but the same error occurs.

I appreciate any help!

Answer
train.user$age <- unlist(train.user$age)

Technically, a data.frame is a list of equal-length vectors, but most functions will assume that all of the columns are atomic vectors and will fail when you try to use a list.

NB: Don't edit an answer into your question.

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