r - Combine the distinct output in 1 row

Question

The code below allows me to see which e-learning module is accessed per day.

activity_per_day_which_modules <- ddply(activity, ~Date, distinct, `Which module(s)` = Module)

The output is as follows:

Date	Module
22-10-2021	Food chemistry
22-10-2021	Food Physics

How do I tell R to combine the rows into one?

Date	Module
22-10-2021	Food chemistry, Food physics
23-10-2021	Food chemistry

score 0 · Accepted Answer · answered Oct 22 '21 at 10:20

You can simply use paste for this:

library(dplyr)

df %>%
  group_by(Date) %>%
  summarize(Module = paste(Module, collapse = ", "))

Note: If your real data has more columns you might want to resort to mutate rather than summarize, if you do just make sure to do %>% distinct() afterwards

r - Combine the distinct output in 1 row

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