[R] Seasonal weekly average

[MacQueen, Don]

I would just add, see
   ?strptime
for information about those date format specifications (  "%V" for example),
and an introduction to R's handling of date and date-time values.

And a few quick examples, to see that %V works as advertised:

> format( Sys.Date() , '%V')
[1] "19"
> format( as.Date('2018-1-1') , '%V')
[1] "01"
> format( as.Date('2018-1-8') , '%V')
[1] "02"

-Don

--
Don MacQueen
Lawrence Livermore National Laboratory
7000 East Ave., L-627
Livermore, CA 94550
925-423-1062
Lab cell 925-724-7509
 
 

On 5/9/18, 1:49 AM, "R-help on behalf of Jim Lemon" <r-help-bounces using r-project.org on behalf of drjimlemon using gmail.com> wrote:

    Hi Shakeel,
    Assuming that you are starting with a bunch of dates:
    
    # make a vector of character strings that can be converted to dates
    rep_dates<-paste(sample(1:30,500,TRUE),sample(1:12,500,TRUE),
     sample(2013:2017,500,TRUE),sep="/")
    # if this isn't your format, change it
    date_format<-"%d/%m/%Y"
    # create a data frame with a column of dates
    rep_df<-data.frame(rep_dates=as.Date(rep_dates,format=date_format))
    # add the week of the year
    rep_df$rep_week<-format(rep_df$rep_dates,"%V")
    # add the year
    rep_df$rep_year<-format(rep_df$rep_dates,"%Y")
    # get a table of the weekly counts by year
    rep_tab<-table(rep_df$rep_week,rep_df$rep_year)
    # get the row means (5 year averages)
    rep5<-apply(rep_tab,1,mean)
    # plot the 5 year weekly averages
    plot(rep5,type="b",ylim=c(0,4),xlab="Week",ylab="Reports per week")
    # add the 2017 weekly counts
    points(rep_tab[,5],type="b",col="red")
    legend(1,4,c("5 yr average","2017"),pch=1,lty=1,col=c("black","red"))
    
    Jim
    
    
    On Wed, May 9, 2018 at 4:37 PM, Shakeel Suleman
    <Shakeel.Suleman using phe.gov.uk> wrote:
    > Hi,
    >
    > I am fairly new to 'R' and would like advice on the following. I want to calculate a weekly average number of reports (e.g. of flu, norovirus) based on the same weeks for the last five years. I will then use this to plot a chart with 52 points for the average based on the last five years; another line will then plot the current year, enabling a comparison of current weekly counts against a five  year average for the same week. I would like some advice on how this can be done in 'R' . My data is disaggregated data - with dates in the format in 01/01/2018.
    >
    > Thanks
    >
    > Shakeel Suleman
    >
    >
    >
    > **************************************************************************
    > The information contained in the EMail and any attachments is confidential and intended solely and for the attention and use of the named addressee(s). It may not be disclosed to any other person without the express authority of Public Health England, or the intended recipient, or both. If you are not the intended recipient, you must not disclose, copy, distribute or retain this message or any part of it. This footnote also confirms that this EMail has been swept for computer viruses by Symantec.Cloud, but please re-sweep any attachments before opening or saving. http://www.gov.uk/PHE
    > **************************************************************************
    >         [[alternative HTML version deleted]]
    >
    > ______________________________________________
    > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
    > https://stat.ethz.ch/mailman/listinfo/r-help
    > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
    > and provide commented, minimal, self-contained, reproducible code.
    
    ______________________________________________
    R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
    https://stat.ethz.ch/mailman/listinfo/r-help
    PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
    and provide commented, minimal, self-contained, reproducible code.