I have a data frame in 2 columns
userID itemID
1 101
1 103
1 107
2 102
2 103
3 104
...
The output I want is to write a file to result.txt
1 \t 101 , 103 , 107
2 \t 102 , 103
3 \t 104
here \t means a tab distance between userID and the itemID. This is not as aligned as a table. I am more of Java and Python background, what are the lower level writing commands in R for general purpose?
you can use dplyr package for this
library(dplyr)
df.summary <- df %.%
group_by(userId) %.%
summarise(itemId = paste(itemId, collapse = ","))
write.table(x=df.summary,file='new_file.tsv',sep='\t',row.names=F)
A bit messy, but this will do the trick, writing the output to output.txt:
d <- read.table(text='userID itemID
1 101
1 103
1 107
2 102
2 103
3 104', header=T)
cat(sapply(split(d, d$userID), function(x)
paste(x$userID[1], paste(x$itemID, collapse=' , '), sep='\t')),
sep='\n', file='output.txt')
See ?cat and ?paste for further details.
Here's another base solution using aggregate:
> write.table(aggregate(d$itemID, list(d$userID), paste, collapse=' , '),
file='result.txt', sep='\t', col.names=FALSE, row.names=FALSE, quote=FALSE)
1 101 , 103 , 107
2 102 , 103
3 104
