sorry, typo
(diff.w<-(as.numeric(dates-st.date)+1)%/%7)
should have been

(diff.w<-as.numeric(dates-st.date)%/%7)


Marco Helbich schrieb:
Hello Eik,

sorry that I contact you again, but I have still a problem with my dates. I need a numeric starting point begining at 01-08-2005 (DDMMYYYY) for every case as a seperate column. E.g:

date                day
01-08-2005      1
01-08-2005      1
02-08-2005      2
20-08-2005    20

Thank you for help and bear with me - I am a newbie!
Best regards
Marco

----- Original Message ----- From: "Eik Vettorazzi" <e.vettora...@uke.uni-hamburg.de>
To: "Marco Helbich" <marco.helb...@gmx.at>
Cc: <r-help@r-project.org>
Sent: Tuesday, April 07, 2009 4:24 PM
Subject: Re: [R] calculate weeks for 2005 and aggregate them


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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Institut für Medizinische Biometrie und Epidemiologie
Universitätsklinikum Hamburg-Eppendorf

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