R write list to CSV line by line - r

Question

I have the following code in R:
library(party)
dat = read.csv("data.csv", header = TRUE)
train <- dat[1:1000, ]
test <- dat[1000:1200, ]
output.tree <- cforest(t_class ~ var1 + var2,
data = train)
train_predict <- predict(output.tree, newdata = test, OOB=TRUE, type = "prob")
for (name in names(train_predict))
{
p <- (train_predict[[name]][1:3])
write.table(p, file = "result.csv",col.names = FALSE, append=TRUE)
}
I am trying to write the result of the random forest prediction to a csv file.
The result train_predict looks like the following:
When I run the above code its only write the first column of each row to the csv and not all three.
How can I write all three columns of the list to the file?
Also is there a way in R to clear the csv before you write to it in case there is something in it already?

Answer 1

Rather than write serially, you can convert to a data.frame and just write all at once:
Generate fake data that looks similar to what you posted:
fakeVec <- function(dummy) t(setNames(rnorm(3), letters[1:3]))
my_list <- lapply(0:4, fakeVec)
names(my_list) <- 6000:6004
Here's the fake data:
$`6000`
a b c
[1,] -0.2444195 -0.2189598 -1.442364
$`6001`
a b c
[1,] 0.2742636 1.068294 -0.8335477
$`6002`
a b c
[1,] -1.13298 1.927268 -2.123603
$`6003`
a b c
[1,] 0.8260184 1.003259 -0.003590849
$`6004`
a b c
[1,] -0.2025963 0.1192242 -1.121807
Then convert format:
# crush to flat matrix
my_mat <- do.call(rbind, my_list)
# add in list names as new column
my_df <- data.frame(id = names(my_list), my_mat)
Now you have a data.frame like this:
id a b c
1 6000 -0.2444195 -0.2189598 -1.442364429
2 6001 0.2742636 1.0682937 -0.833547659
3 6002 -1.1329796 1.9272681 -2.123603334
4 6003 0.8260184 1.0032591 -0.003590849
5 6004 -0.2025963 0.1192242 -1.121807439
Which you can just write straight to a file:
write.csv(my_df, 'my_file.csv', row.names=F)

Answer 2

How about this?
temp = list(x = data.frame(a = "a", b = "b", c = "c"),
y = data.frame(d = "d", e = "e", f = "f"),
z = data.frame(g = "g", h = "h", i = "i"))
for (i in 1:length(temp)) {
write.table(temp[[i]], "temp.csv",col.names = F, append = T)
}
Regarding clearing the csv. If I understood your question correctly, just erase the append = T?