[R] calculate weeks for 2005 and aggregate them

[Eik Vettorazzi]

Hi Marco,
try
date <- c("20-08-2005", "27-08-2005", "19-08-2005", "29-08-2005", 
"01-08-2005", "01-08-2005",
 "25-08-2005", "15-08-2005", "11-08-2005", "12-08-2005", "18-08-2005", 
"02-08-2005",
 "04-08-2005", "15-08-2005", "17-08-2005", "24-08-2005", "15-08-2005", 
"30-08-2005",
 "30-08-2005", "02-08-2005", "05-08-2005", "04-08-2005", "22-08-2005", 
"11-08-2005",
 "25-08-2005", "29-08-2005", "07-08-2005", "04-08-2005", "08-08-2005", 
"08-08-2005")
# your given crime-"factor" had only 3 entries
hcrime <- factor(sample(1:3,length(date),replace=T),labels=c("Aggravated 
Assault", "Burglary", "Robbery"))

#depending on your starting day of a week you could also use "%U% 
instead of "%W", see ?strftime
week<-as.factor(format(as.Date(date,"%d-%m-%Y"),"%W"))

#step 2 and 3
table(week,hcrime)

but you should explain why 27-08-2005 will lead to week=99?!

hth.


Marco Helbich schrieb:
> Dear list,
>
> here is an example of my dataset:
>
> date <- c("20-08-2005", "27-08-2005", "19-08-2005", "29-08-2005", 
> "01-08-2005", "01-08-2005",
>  "25-08-2005", "15-08-2005", "11-08-2005", "12-08-2005", "18-08-2005", 
> "02-08-2005",
>  "04-08-2005", "15-08-2005", "17-08-2005", "24-08-2005", "15-08-2005", 
> "30-08-2005",
>  "30-08-2005", "02-08-2005", "05-08-2005", "04-08-2005", "22-08-2005", 
> "11-08-2005",
>  "25-08-2005", "29-08-2005", "07-08-2005", "04-08-2005", "08-08-2005", 
> "08-08-2005")
> hcrime <- factor(c("Aggravated Assault", "Burglary", "Robbery"))
> data <- cbind(date, hcrime)
>
> I have following questions:
> a) how can I find out the weeks of every date
> b) aggregate the dates falling in the same week
> c) sum up the different crimes per week
>
> for better understanding here is an example for a) and b):
> date                    week
> 27-08-2005            99
> 27-08-2005            99
> 29-08-2005            99
>
> and here one for c):
>
> week    crimes_Robbery    crimes_Robbery
> 98                2                            1
> 99                3                            0
>
> thank you very much for your help!
> best regards
> Marco
>
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-- 
Eik Vettorazzi
Institut für Medizinische Biometrie und Epidemiologie
Universitätsklinikum Hamburg-Eppendorf

Martinistr. 52
20246 Hamburg

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