Question

I have a data frame, with only one column, and I want to turn it into a two column by selecting only certain rows, here…let me show you

I want to go from this

       V1   
1    one
2    two
3    &&three
4    four
5    &&five
6    six

to this

     V1      V2
1    one     NA
2    two     three
3    four    five
4    six     NA

So the ones that have a && are placed in column two, to the right of the above row (hope that makes sense). Is there any way I can do this?

Answer 1

Here’s my approach:

Read in the data:

dat <- read.table(text="       V1   
1    one
2    two
3    &&three
4    four
5    &&five
6    six", head=T, stringsAsFactors = FALSE)

The reshaping:

j <- grep("&&", dat$V1)                                 #find && rows
l <- j-1                                                #find rows above && rows
dat$V2 <- rep(NA, nrow(dat))                            #create NA vector
dat$V2[l] <- gsub("&&", "", dat[grep("&&", dat$V1), 1]) #see what it does :)
dat2 <- dat[-j, ]                                       #get rid of the && rows
rownames(dat2) <- 1:nrow(dat2)                          #rename rows

Which yields:

    V1    V2
1  one  <NA>
2  two three
3 four  five
4  six  <NA>