Collapse all columns by an ID column [duplicate]

Answer 1

Here's an option using summarise_each (which makes it easy to apply the changes to all columns except the grouping variables) and toString:

require(dplyr)

have %>%
  group_by(ID) %>%
  summarise_each(funs(toString))

#Source: local data frame [5 x 3]
#
#     ID          info1                          info2
#1 id101            one                          first
#2 id102     twoA, twoB second alias A, second alias B
#3 id103 threeA, threeB   third alias A, third alias B
#4 id104           four                         fourth
#5 id105           five                          fifth

Or, if you want it separated by semicolons, you can use:

have %>%
  group_by(ID) %>%
  summarise_each(funs(paste(., collapse = "; ")))