[R] Seasonal weekly average

MacQueen, Don m@cqueen1 @end|ng |rom ||n|@gov
Wed May 9 17:40:25 CEST 2018


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
    >
    >
    >
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