Aggregate function taking into account a non-numeric variable

[forlornfortress]

Hi guys!

I have a dataframe with 6 variables: four non-numeric (one of them is the station code and is the one I want to use. There are 62 codes), one variable for the date in %Y-%m-%d %H:%M:%S format (from 2000 to 2017) and the other which is the concentration of tropospheric ozone.
I am using the aggreggate function as I want to calculate the summation of the concentration for each year and for each station code.
For the moment I have tried this:

aggregate(aot40_3$AOT40, list(Date = cut(as.Date(aot40_3$date, format="%Y-%m-%d %H:%M:%S"), breaks="1 year")), FUN=sum)

What this does is sum every year taking into account all the stations, but I need to consider the stations separately.

Thanks in advance!!

[Yarnabrina]

Hi!

The problem with your code is that you are not telling aggregate to take into account the station codes at all. So why do you think it will do so all by itself? If I understand your question correctly, then this might help:

set.seed(seed = 48250)

fake_dataset <- data.frame(ozone_concentrations = rexp(n = 100),
                           station_codes = sample.int(n = 10,
                                                      size = 100,
                                                      replace = TRUE),
                           date_times = sample(x = seq(from = as.POSIXct(x = "2000-01-01 00:00:00"),
                                                       to = as.POSIXct(x = "2005-12-31 23:59:59"),
                                                       by = "sec"),
                                               size = 100,
                                               replace = TRUE))

aggregate(formula = (ozone_concentrations ~ station_codes + years),
          data = transform(`_data` = fake_dataset,
                           years = substr(x = date_times,
                                          start = 1,
                                          stop = 4)),
          FUN = sum)
#>    station_codes years ozone_concentrations
#> 1              2  2000          0.064241865
#> 2              3  2000          3.391680050
#> 3              5  2000          1.000316242
#> 4              6  2000          0.561307493
#> 5              7  2000          3.528994244
#> 6              8  2000          2.756995374
#> 7              9  2000          5.609195160
#> 8             10  2000          1.264838466
#> 9              1  2001          1.779377927
#> 10             2  2001          2.289763227
#> 11             3  2001          2.161737537
#> 12             4  2001          1.117474744
#> 13             5  2001          1.599183055
#> 14             6  2001          0.150858606
#> 15             9  2001          3.168106966
#> 16             2  2002          1.011305285
#> 17             3  2002          7.791112683
#> 18             4  2002          0.005795882
#> 19             5  2002          3.390604591
#> 20             6  2002          1.898864461
#> 21             7  2002          0.155775124
#> 22             8  2002          3.111518933
#> 23             9  2002          1.935719344
#> 24             1  2003          3.530518554
#> 25             3  2003          3.136105068
#> 26             4  2003         13.354189556
#> 27             5  2003          0.291728424
#> 28             6  2003          0.503696389
#> 29             7  2003          0.740147266
#> 30             8  2003          1.442953513
#> 31            10  2003          3.393911725
#> 32             1  2004          3.108035615
#> 33             2  2004          0.719082672
#> 34             3  2004          0.135565576
#> 35             4  2004          0.349281420
#> 36             5  2004          0.629870183
#> 37             6  2004          3.963184938
#> 38             7  2004          1.852908889
#> 39             8  2004          3.048067579
#> 40             9  2004          2.390117817
#> 41            10  2004          1.088342140
#> 42             1  2005          0.238723134
#> 43             3  2005          0.398160109
#> 44             4  2005          1.044262535
#> 45             6  2005          3.298614198
#> 46             7  2005          2.816752607
#> 47             8  2005          5.153532699
#> 48             9  2005          1.522409497
#> 49            10  2005          1.115334160

^{Created on 2019-12-30 by the reprex package (v0.3.0)}