r - Create new rows in data frame based on multiple values of column -

i have adjusted question bit more specific

i have searched specific answer question without success.

first of have data frame consisting of 48 variables, looks likes this:

> df      text                                               screen_name   ...   1   text @sam , @su , @jim addressed   peter 2   text @eric addressed                    margret 3   text @sarah , @adam addressed        john 

now extracting strings equal ("@\s+") , store them in new column

df$addressees <- str_extract_all(df$text, "@\\s+") 

this gets me:

    ...   screen_name   addressees               ...   1         peter         c("@sam", "@su", "@jim") 2         margret       @eric 3         john          c("@sarah", "@adam") 

now want create new data frame 2 columns new rows each "addressee" created repeating respective value of column "screen_name":

> df      screen_name  addressees  1  peter        sam  2  peter        su  3  peter        jim  4  margret      eric  5  john         sarah  6  john         adam 

i have tried solutions similar approaches, none of them seems work.

thank help!

ok, reproducible example:

# create df ego <- c("peter","margaret","john") friends <- list(c("sam","su","jim"),c("eric"),c("sarah","adam")) df <- data.frame(ego,friends= i(friends),stringsasfactors = f)  # use repeat function repeat rows times <- sapply(df$friends,length) df <- df[rep(seq_len(nrow(df)), times),] # assign unlisted friends df$friends <- unlist(friends)