How to flag last friday or last day or month

Question

I have a data frame of dates and the day of the week

> head(data)
         day   weekday
1 2016-01-01    Friday
4 2016-01-04    Monday
5 2016-01-05   Tuesday
         


        

Answer 1

library(lubridate)
library(dplyr)
data%>% 
  mutate(year = year(day),month= month(day)) %>%
  group_by(year, month) %>% 
  mutate(LastDayInMonth = max(day)==day)%>% 
  arrange(day) %>%
  ungroup() %>% 
  group_by(year, month, weekday) %>%
  mutate(LastWeekInMonth = row_number() ==  n(), 
         LastFriayInMonth = weekday =="Freitag" & LastWeekInMonth == 1) %>% 
  ungroup()%>%
  select(day, weekday, LastDayInMonth,LastFriayInMonth)

Same excerpt as above (%>% filter(LastDayInMonth | LastFriayInMonth == TRUE):

Source: local data frame [8 x 4]

         day    weekday LastDayInMonth LastFriayInMonth
      (date)     (fctr)          (lgl)            (lgl)
1 2016-01-29    Freitag           TRUE             TRUE
2 2016-02-26    Freitag          FALSE             TRUE
3 2016-02-29     Montag           TRUE            FALSE
4 2016-03-25    Freitag          FALSE             TRUE
5 2016-03-31 Donnerstag           TRUE            FALSE
6 2016-04-29    Freitag           TRUE             TRUE
7 2016-05-06    Freitag          FALSE             TRUE
8 2016-05-10   Dienstag           TRUE            FALSE