I'm trying to compare my model data with field data in r. Field data is at certain depths(1,20,50,75,100,150..). Model data output is not at the same depths and have to be interpolated(linear) and preferably added to a new column in the field data.
I would like to run a for loop on each row of the model data and use the approx function to interpolate data to fit the depths of the field data and add it to the model_chla column. I have extracted the same dates(19 dates) from both data sets, so only interpolation on model depth is necesarry.
chla_FIELD # some of the field data with the empty model column
date depth chla model_chla
1 2008-02-21 1 0.06 NA
2 2008-02-21 20 0.05 NA
3 2008-02-21 50 0.03 NA
4 2008-02-27 1 0.08 NA
5 2008-02-27 20 0.04 NA
6 2008-02-27 50 0.03 NA
7 2008-02-27 75 0.03 NA
8 2008-02-27 100 0.01 NA
9 2008-03-07 1 0.07 NA
10 2008-03-07 20 0.05 NA
11 2008-03-07 50 0.03 NA
12 2008-03-07 75 0.02 NA
13 2008-03-07 100 0.02 NA
14 2008-03-07 150 0.01 NA
chla_MODEL # Some of the model data to be interpolated to field data depths and added to column
dt depth chla
766 2008-02-21 1.0 0.22385520
767 2008-02-21 7.5 0.21676594
768 2008-02-21 15.0 0.19189246
769 2008-02-21 25.0 0.15524526
770 2008-02-21 40.0 0.14638090
771 2008-02-21 62.5 0.14301939
772 2008-02-21 87.5 0.14094244
773 2008-02-21 112.5 0.13897014
774 2008-02-21 137.5 0.13680272
775 2008-02-21 162.5 0.13430916
776 2008-02-21 187.5 0.13133907
777 2008-02-21 212.5 0.12757768
778 2008-02-21 237.5 0.12237051
779 2008-02-21 262.5 0.11396441
780 2008-02-21 287.5 0.09206185
856 2008-02-27 1.0 0.24240938
857 2008-02-27 7.5 0.23447734
858 2008-02-27 15.0 0.21238998
859 2008-02-27 25.0 0.15545718
860 2008-02-27 40.0 0.14592259
861 2008-02-27 62.5 0.14171122
862 2008-02-27 87.5 0.13900438
863 2008-02-27 112.5 0.13662824
My start is something like this, but I'm new to the approx function and adding data to columns in loops.
chla_approx <- function(FieldDATA, ModelDATA)
for (row in FieldDATA) {
}
Or is there an easier way to do this? Thanks!
The following code assumes that all dates in chla_FIELD are present in chla_MODEL.
If the dates in the data sets are already of class "Date" these two instructions are not needed.
chla_FIELD$date <- as.Date(chla_FIELD$date)
chla_MODEL$dt <- as.Date(chla_MODEL$dt)
Now split/apply/combine.
sp_field <- split(chla_FIELD, chla_FIELD$date)
sp_model <- split(chla_MODEL, chla_MODEL$dt)
approx_fun_list <- lapply(sp_model, function(data){
approxfun(data[["depth"]], data[["chla"]])
})
chla_FIELD <- lapply(names(sp_field), function(nm){
f <- approx_fun_list[[nm]]
sp_field[[nm]]$model_chla <- f(sp_field[[nm]]$depth)
sp_field[[nm]]
})
chla_FIELD <- do.call(rbind, chla_FIELD)
Final cleanup.
rm(sp_field, sp_model)