Using the result of summarise (dplyr) to mutate the original dataframe

Question

I have a rather big dataframe with a column of POSIXct datetimes (~10yr of hourly data). I would flag all the rows in which the day falls in a Daylight saving period. For ex

Answer 1

The best solution to get the job done, as suggested by @aosmith, is.

limits = span %>% group_by(YEAR) %>% mutate(minDOY=min(DOY[DLS]),maxDOY=max(DOY[DLS]),CHECK=FALSE)

limits$CHECK[(limits2$DOY >= limits$minDOY) & (limits$DOY <= limits$maxDOY) ] = TRUE

The use of the ave function is a good choice, but I personally prefer to stick to the 'dplyr' package.