How to merge specific rows that match a grep pattern - r

Question

I have a dataframe as follows:
Jen Rptname freq
AKT bilb1 23
AKT bilb1 234
DFF bilb22 987
DFF bilf34 7
DFF jhs23 623
AKT j45 53
JFG jhs98 65
I know how to group the whole dataframe based on individual columns but how do I merge individual rows based on a grep (in this case bilb.* and jhs.*)
I want to be able to merge the rows (and therefore also add the frequencies together) with bilb* and separately the rows with jhs* so that I end up with
AKT bilb 257
DFF bilb 987
DFF bilf34 7
DFF jhs 623
AKT j45 53
JFG jhs 65
This is so that the aggregation is by Jen and Rptname so I can see how many of the same Rptnames are in each Jen

Answer 1

We can use grep to get the index of 'Rptname' elements that have 'bilb' or 'jhs', remove the numeric part with sub and use aggregate to get the sum of 'Freq' by 'Rptname'
indx <- grep('bilb|jhs', df1$Rptname)
df1$Rptname[indx] <- sub('\\d+', '', df1$Rptname[indx])
aggregate(freq~Rptname, df1, FUN=sum)
# Rptname freq
#1 bilb 1244
#2 bilf34 7
#3 j45 53
#4 jhs 688
Update
Suppose your dataset is 'df2'
df2$grp <- gsub("([A-Z]+|[a-z]+)[^A-Z]+", "\\1", df2$Rptname)
aggregate(freq~grp+Jen, df2, FUN=sum)
data
df1 <- structure(list(Rptname = c("bilb1", "bilb1", "bilb22",
"bilf34",
"jhs23", "j45", "jhs98"), freq = c(23L, 234L, 987L, 7L, 623L,
53L, 65L)), .Names = c("Rptname", "freq"), class = "data.frame",
row.names = c(NA, -7L))
df2 <- structure(list(Jen = c("AKT", "AKT", "AKT", "DFF", "DFF",
"DFF",
"DFF", "DFF", "DFF", "AKT", "JFG", "JFG", "JFG"), Rptname = c("bilb1",
"bilb1", "bilb22", "bilb22", "bilb1", "BTBy", "bilf34", "BTBx",
"jhs23", "j45", "jhs98", "BTBfd", "BTBx"), freq = c(23L, 234L,
22L, 987L, 18L, 18L, 7L, 9L, 623L, 53L, 65L, 19L, 14L)),
.Names = c("Jen",
"Rptname", "freq"), class = "data.frame", row.names = c(NA, -13L))

Answer 2

Similar to akrun's and I like his use of aggregate better than my creation of an intermediate vector:
> inter <- tapply(dat$freq, sub("^(bilb|jhs)(.+)$", "\\1", dat$Rptname) ,sum)
> final <- data.frame( nams = names(inter), sums = inter)
> final
nams sums
bilb bilb 1244
bilf34 bilf34 7
j45 j45 53
jhs jhs 688
My pattern would require that the 'bilb' amd 'jhs' be at the beginning of the value. Remove the "^" if that was not intended, but if so, add a "(.*)" and switch to "\\2" in the replacement.