Replace the rows in dataframe with condition - r

Question

Hi in relation to the question here:
[Dynamically replace row in dataframe with vector
I have a data.frame for example:
d <- read.table(text=' V1 V2 V3 V4 V5 V6 V7
1 1 a 2 3 4 9 6
2 1 b 2 2 4 5 NA
3 1 c 1 3 4 5 8
4 1 d 1 2 3 6 9
5 2 a 1 2 3 4 5
6 2 b 1 4 5 6 7
7 2 c 1 2 3 5 8
8 2 d 2 3 6 7 9', header=TRUE)
Now I want to take one row, for example the first one (1a) and:
Get the min and max value from that row. In this case min=2 and max=9 (note there are missing values in between for example there is no 5, 7, or 8 in that row).
Now I want to replace that row with all missing values and extend it (the row will be longer than all others as it will go from 2 until 9 (2,3,4,5,6,7,8,9). The whole data.frame should then be automatically extended by NA columns for the other rows that are not as long as the one I replaced.
Now the following code does achieve this:
row.to.change <- 1
(new.row <- seq(min(d[row.to.change,c(-1, -2)], na.rm=TRUE), max(d[row.to.change,c(-1,-2)], na.rm=TRUE)))
(num.add <- length(new.row) - ncol(d) + 2)
# [1] 3
if (num.add > 0) {
d <- cbind(d, replicate(num.add, rep(NA, nrow(d))))
} else if (num.add <= 0) {
new.row <- c(new.row, rep(NA, -num.add))
}
and finally renames the extended data.frame headers as the default ones:
d[row.to.change,c(-1, -2)] <- new.row
colnames(d) <- paste0("V", seq_len(ncol(d)))
Now: This does work for the row that I specify in: row.to.replace but how does this work, if for example I want it to work for all rows which have a 'b' in the second column? Something like: "do this where d$V2 == 'b'"? In case the data.frame is 5000 rows long.

Answer 1

You have already solved. Just make a function and then apply it to each row of your data.
rtc=function(row.to.change){# <- 1
(new.row <- seq(min(d[row.to.change,c(-1, -2)], na.rm=TRUE), max(d[row.to.change,c(-1,-2)], na.rm=TRUE)))
(num.add <- length(new.row) - ncol(d) + 2)
# [1] 3
if (num.add <= 0) {
new.row <- c(new.row, rep(NA, -num.add))
}
new.row
}
#d2=d
newr=lapply(1:nrow(d),rtc) # for the hole data
# for specific condition, like lines with "b" in V2 change to:
# newr=lapply(1:nrow(d),function(z)if(d$V2[z]=="b")rtc(z) else as.numeric(d[z,c(-1, -2)]))
mxl=max(sapply(newr,length))
newr=lapply(newr,function(z)if(length(z)<mxl)c(z,rep(NA,mxl-length(z))) else z)
if (ncol(d)-2 < mxl) {
d <- cbind(d, replicate(mxl-ncol(d)+2, rep(NA, nrow(d))))
}
d[,c(-1, -2)] <- do.call(rbind,newr)
colnames(d) <- paste0("V", seq_len(ncol(d)))
d
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11
1 1 a 2 3 4 5 6 7 8 9 NA
2 1 b 2 3 4 5 NA NA NA NA NA
3 1 c 1 2 3 4 5 6 7 8 NA
4 1 d 1 2 3 4 5 6 7 8 9
5 2 a 1 2 3 4 5 NA NA NA NA
6 2 b 1 2 3 4 5 6 7 NA NA
7 2 c 1 2 3 4 5 6 7 8 NA
8 2 d 2 3 4 5 6 7 8 9 NA