Replacing rows in R - r

Question

In R am reading a file with comments as csv using
read.data.raw = read.csv(inputfile, sep='\t', header=F, comment.char='')
The file looks like this:
#comment line 1
data 1<tab>x<tab>y
#comment line 2
data 2<tab>x<tab>y
data 3<tab>x<tab>y
Now I extract the uncommented lines using
comment_ind = grep( '^#.*', read.data.raw[[1]])
read.data = read.data.raw[-comment_ind,]
Which leaves me:
data 1<tab>x<tab>y
data 2<tab>x<tab>y
data 3<tab>x<tab>y
I am modifying this data through some separate script which maintains the number of rows/cols and would like to put it back into the original read data (with the user comments) and return it to the user like this
#comment line 1
modified data 1<tab>x<tab>y
#comment line 2
modified data 2<tab>x<tab>y
modified data 3<tab>x<tab>y
Since the data I extracted in read.data preserves the row names row.names(read.data), I tried
original.read.data[as.numeric(row.names(read.data)),] = read.data
But that didn't work, and I got a bunch of NA/s
Any ideas?

Answer 1

Does this do what you want?
read.data.raw <- structure(list(V1 = structure(c(1L, 3L, 2L, 4L, 5L),
.Label = c("#comment line 1", "#comment line 2", "data 1", "data 2",
"data 3"), class = "factor"), V2 = structure(c(1L, 2L, 1L, 2L, 2L),
.Label = c("", "x"), class = "factor"), V3 = structure(c(1L, 2L, 1L,
2L, 2L), .Label = c("", "y"), class = "factor")), .Names = c("V1",
"V2", "V3"), class = "data.frame", row.names = c(NA, -5L))
comment_ind = grep( '^#.*', read.data.raw[[1]])
read.data <- read.data.raw[-comment_ind,]
# modify V1
read.data$V1 <- gsub("data", "DATA", read.data$V1)
# rbind() and then order() comments into original places
new.data <- rbind(read.data.raw[comment_ind,], read.data)
new.data <- new.data[order(as.numeric(rownames(new.data))),]