Concatenate row-wise across specific columns of dataframe
apply, paste, r, sapply, string-concatenation
Solution
Try
data$id <- paste(data$F, data$E, data$D, data$C, sep="_")
instead. The beauty of vectorized code is that you do not need row-by-row loops, or loop-equivalent *apply functions.
Edit Even better is
data <- within(data, id <- paste(F, E, D, C, sep=""))
Problem
I have a data frame with columns that, when concatenated (row-wise) as a string, would allow me to partition the data frame into a desired form. ``` > str(data) 'data.frame': 680420 obs. of 10 variables: $ A : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ... $ B : chr "2011-01-26" "2011-01-27" "2011-02-09" "2011-02-10" ... $ C : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ... $ D : chr "AAA" "AAA" "BCB" "CCC" ... $ E : chr "A00001" "A00002" "B00002" "B00001" ... $ F : int 9 9 37 37 37 37 191 191 191 191 ... $ G : int NA NA NA NA NA NA NA NA NA NA ... $ H : int 4 4 4 4 4 4 4 4 4 4 ... ``` For each row, I would like to concatenate the data in columns F, E, D, and C into a string (with the underscore character as separator). Below is my unsuccessful attempt at this: ``` data$id <- sapply(as.data.frame(cbind(data$F,data$E,data$D,data$C)), paste, sep="_") ``` And below is the undesired result: ``` > str(data) 'data.frame': 680420 obs. of 10 variables: $ A : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ... $ B : chr "2011-01-26" "2011-01-27" "2011-02-09" "2011-02-10" ... $ C : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ... $ D : chr "AAA" "AAA" "BCB" "CCC" ... $ E : chr "A00001" "A00002" "B00002" "B00001" ... $ F : int 9 9 37 37 37 37 191 191 191 191 ... $ G : int NA NA NA NA NA NA NA NA NA NA ... $ H : int 4 4 4 4 4 4 4 4 4 4 ... $ id : chr [1:680420, 1:4] "9" "9" "37" "37" ... ..- attr(*, "dimnames")=List of 2 .. ..$ : NULL .. ..$ : chr "V1" "V2" "V3" "V4" ``` Any help would be greatly appreciated.