Вот как это сделать с dplyr
и lubridate
:
library(dplyr)
library(lubridate)
# generate a data frame with dates to play with
(df <- data_frame(
date=seq(as.Date("2017-01-01"), as.Date("2018-12-31"), by=6),
amount=rgamma(length(date), shape=2, scale=20)))
df %>%
group_by(month=floor_date(date, "month")) %>%
summarize(date = max(date))