[R] Loop With Dates

[Jim Lemon]

Hi Phillip,
While I really like Ana's solution, this might also help:

phdf<-read.table(text="Date count
  2018-03-29     1
  2018-03-29     1
  2018-03-29     1
  2018-03-30     1
  2018-03-30     1
  2018-03-30     1
  2018-03-31     1
  2018-03-31     1
  2018-03-31     1",
  header=TRUE,stringsAsFactors=FALSE)
phdf$Date<-as.Date(phdf$Date,"%Y-%m-%d")
incflag<-diff(phdf$Date)>0
phdf$count<-c(NA,cumsum(incflag)+1)

Jim

On Sat, Sep 21, 2019 at 3:47 AM Phillip Heinrich <herd_dog using cox.net> wrote:
>
> With the data snippet below I’m trying to increment the “count” vector by one each time the date changes.
>
>          Date count
> 1   2018-03-29     1
> 2   2018-03-29     1
> 3   2018-03-29     1
> 81  2018-03-30     1
> 82  2018-03-30     1
> 83  2018-03-30     1
> 165 2018-03-31     1
> 166 2018-03-31     1
> 167 2018-03-31     1
>
>
>             >
>
>
>
> I can get count to change when the date changes with the following code:
>
> test2 <- transform(test2,
> +                   count = ifelse(Date == lag(Date,1),count,count+1))
> > test2
>           Date count
> 1   2018-03-29    NA
> 2   2018-03-29     1
> 3   2018-03-29     1
> 81  2018-03-30     2
> 82  2018-03-30     1
> 83  2018-03-30     1
> 165 2018-03-31     2
> 166 2018-03-31     1
> 167 2018-03-31     1
>
>
>
>
>
>
>
> ...but I want all three March 30 rows to have a count of 2 and the March 31 rows to be equal to 3.  Any suggestions?
>
> Thanks.
>         [[alternative HTML version deleted]]
>
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