[R] beginner question: subset first entry (row) per week

[Bert Gunter]

new.df <- orig.df[!duplicated(df[["week"]]), ]

See ?duplicated

-- Bert
Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Thu, Feb 2, 2017 at 1:04 PM, Dagmar <Ramgad82 at gmx.net> wrote:
> Dear knowing people,
>
> I have a data frame like this.
>
> exdatframe <- data.frame(Name=c("Ernie","Ernie","Ernie",
> "CookieMonster","CookieMonster","CookieMonster"),
> recordedTime=as.POSIXct(strptime(as.character("01.01.2017","02.01.2011","03.01.2011",
> "01.01.2011","02.01.2011","03.01.2011"),"%d.%m.%Y")),
>                          week =c(1,2,2,
>                                 1,2,2),
>                          eatencookies=c(1,0.5,0.001,
>                                        50,51,200))
> exdatframe
>
> #Now I want a new dataframe with only the first row per week (i.e. I want to
> know how many cookies were eaten at the first recorded day of each week).
> Something like that:
>
> exdatframe2 <- data.frame(Name=c("Ernie","Ernie",
> "CookieMonster","CookieMonster"),
>                          recordedTime=c("01.01.2017","02.01.2011",
> "01.01.2011","02.01.2011"),
>                          week =c(1,2,
>                                  1,2),
>                          eatencookies=c(1,0.5,
>                                         50,51))
> exdatframe2
>
> # How do I do that? I thought it must be something with tapply or subset -
> but I just don't get it....
>
> # would be great if someone helps.
>
> # Dagmar
>
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