monthly mean for each month and each year in the data frame
Hi Stefano, What about this? df$months<-format(df$data_POSIX,"%Y-%m") snow_means<-by(df$value,df$months,mean) Jim On Mon, Sep 14, 2020 at 8:19 PM Stefano Sofia
<stefano.sofia at regione.marche.it> wrote:
Dear R-list users,
I know that this is a trivial question, but I already wasted quite a large amount of time on that.
I have a data frame with daily data of snow fall. I need to evaluate the monthly mean for each month and each year in the data frame.
Could you help me to find an eficient way for these calculations?
Thank you for your help
Stefano
Here a reproducibile code:
first_day_1 <- as.POSIXct("2019-01-19-00-00", format="%Y-%m-%d-%H-%M")
last_day_1 <- as.POSIXct("2019-03-20-00-00", format="%Y-%m-%d-%H-%M")
df1 <- data.frame(data_POSIX=seq(first_day_1, last_day_1, by="1 days"))
df1$value <- runif(nrow(df1), 0, 10)
first_day_2 <- as.POSIXct("2020-02-19-00-00", format="%Y-%m-%d-%H-%M")
last_day_2 <- as.POSIXct("2020-04-20-00-00", format="%Y-%m-%d-%H-%M")
df2 <- data.frame(data_POSIX=seq(first_day_2, last_day_2, by="1 days"))
df2$value <- runif(nrow(df2), 0, 10)
df <- rbind(df1, df2)
(oo)
--oOO--( )--OOo----------------
Stefano Sofia PhD
Civil Protection - Marche Region
Meteo Section
Snow Section
Via del Colle Ameno 5
60126 Torrette di Ancona, Ancona
Uff: 071 806 7743
E-mail: stefano.sofia at regione.marche.it
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