r - dplyr on subset of columns while keeping the rest of the data.frame -

i trying use dplyr apply function subset of columns. however, in contrast code per below, trying implement while keeping columns in data-frame. currently, resulting data-frame keeps selected columns. can use remove-and-cbind construction merge these columns original dataframe, wondering if there way directly in dplyr? have tried move select function inside mutate function, not able make work yet.

require(dplyr) replace15=function(x){ifelse(x<1.5,1,x)} dg <- iris %>%   dplyr::select(starts_with("petal")) %>%   mutate_each(funs(replace15))   dg  > dg source: local data frame [150 x 2]     petal.length petal.width 1           1.0           1 2           1.0           1 3           1.0           1 4           1.5           1 5           1.0           1 6           1.7           1 7           1.0           1 8           1.5           1 9           1.0           1 10          1.5           1 

dg <- iris %>% mutate_each(funs(replace15), matches("^petal")) 

alternatively (as posted @aosmith) use starts_with. have @ ?select other special functions available within select, summarise_each , mutate_each.