Às 15:51 de 13/05/2023, Stefano Sofia escreveu:
Dear list users,
I have to aggregate wind direction data (wd) using a function that requires
also a second input variable, wind speed (ws).
This is the function that I need to use:
my_fun <- function(wd1, ws1){
u_component <- -ws1*sin(2*pi*wd1/360)
v_component <- -ws1*cos(2*pi*wd1/360)
mean_u <- mean(u_component, na.rm=T)
mean_v <- mean(v_component, na.rm=T)
mean_wd <- (atan2(mean_u, mean_v) * 360/2/pi) + 180
result <- mean_wd
result
}
Does the aggregate function work only with functions with a single input
variable (the one that I want to aggregate), or its use can be extended to
functions with two input variables?
Here a simple example (which is meaningless, the important think is the concept
behind it):
df <- data.frame(day=c(1, 1, 1, 2, 2, 2, 3, 3), month=c(1, 1, 2, 2, 2, 2, 2,
2), wd=c(45, 90, 90, 135, 180, 270, 270, 315), ws=c(7, 7, 8, 3, 2, 7, 14, 13))
aggregate(wd ~ day + month, data=df, FUN = my_fun)
cannot work, because ws is not taken into consideration.
I got lost. Any hint, any help?
I hope to have been able to explain my problem.
Thank you for your attention,
Stefano
(oo)
--oOO--( )--OOo--------------------------------------
Stefano Sofia PhD
Civil Protection - Marche Region - Italy
Meteo Section
Snow Section
Via del Colle Ameno 5
60126 Torrette di Ancona, Ancona (AN)
Uff: +39 071 806 7743
E-mail: stefano.so...@regione.marche.it
---Oo---------oO----------------------------------------
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Hello,
Use the dots argument to pass any number of named arguments to your
aggregation function.
In this case, ws1 = ws at the end of the aggregate call.
aggregate(wd ~ day + month, data=df, FUN = my_fun, ws1 = ws)
You can also give the user the option to remove or not NA's by adding a
na.rm argument:
my_fun <- function(wd1, ws1, na.rm = FALSE) {
[...]
mean_u <- mean(u_component, na.rm = na.rm)
mean_v <- mean(v_component, na.rm = na.rm)
[...]
}
aggregate(wd ~ day + month, data=df, FUN = my_fun, ws1 = ws, na.rm = TRUE)
Hope this helps,
Rui Barradas
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and provide commented, minimal, self-contained, reproducible code.
