Get monthly means from dataframe of several years of daily temps

Question

I have daily temperature values for several years, 1949-2010. I would like to calculate monthly means. Here is an example of the data:

head(tmeasmax)
TIMESTE         


        

Answer 1

You can use the lubridate package to create a new factor variable consisting of the year-month combinations, then use aggregate.

library('lubridate')

tmeasmax2 <- within(tmeasmax, {
        monthlies <- paste(year(TIMESTEP),
                           month(TIMESTEP))
})

aggregate(tmeasmax2, list(monthlies), mean, na.rm = TRUE)