r - Can't write data frame to database -

i can't create code example because i'm not quite sure problem , actual problem rather involved. said seems kind of generic problem maybe somebody's seen before.

basically i'm constructing 3 different dataframes , rbinding them together, expected smooth sailing when try write merged frame db error:

 error in .external2(c_writetable, x, file, nrow(x), p, rnames, sep, eol,  :     unimplemented type 'list' in 'encodeelement' 

i've tried manually coercing them using as.data.frame() before , after rbinds , returned object (the same 1 fails write above error message) exists in environment class data.frame why dbwritetable not seem have got memo?

sorry, i'm connecting mysql db using rmysql. problem think little closer , try explain myself columns of data frame lists (of same length), sorta makes sense of error. i'd think (or think anyways) call as.data.frame() take care of guess not?

a portion of str() since it's long looks like:

 .. [list output truncated]  $ stcong            :list of 29809 ..$ : int 3 ..$ : int 8 ..$ : int 4 ..$ : int 2 

i guess i'm wondering if there's easy way force coercion?

hard sure, since provided little concrete information, 1 way convert list column atomic vector column:

> d <- data.frame(x = 1:5) > d$y <- as.list(letters[1:5]) > str(d) 'data.frame':   5 obs. of  2 variables:  $ x: int  1 2 3 4 5  $ y:list of 5   ..$ : chr "a"   ..$ : chr "b"   ..$ : chr "c"   ..$ : chr "d"   ..$ : chr "e" > d$y <- unlist(d$y) > str(d) 'data.frame':   5 obs. of  2 variables:  $ x: int  1 2 3 4 5  $ y: chr  "a" "b" "c" "d" ... 

this assumes each element of list column length 1 vector. if aren't, things more complicated, , you'd need rethink data structure anyhow.