Message-ID: <421A59CE-89A5-417B-AF6B-E67A4C802B2C@gmail.com>
Date: 2023-10-24T13:01:51Z
From: Peter Dalgaard
Subject: How to Calculate the Mean by Multiple Groups in R
In-Reply-To: <CAM_vju=jtH=+d8nMb=+DLmZg2mQ2U+4TsOVJ6OJ7jHHWQh5jDA@mail.gmail.com>
Also,
> aggregate(cbind(OD, ODnorm) ~ Time + Target + Conc, data = df, FUN = "mean")
Time Target Conc OD ODnorm
1 1 BACT 1 765.3333 108.33333
2 1 BACT 2 745.3333 88.33333
3 1 BACT 3 675.0000 18.00000
(You might wish for "cbind(OD,ODnorm) ~ . - Well", but aggregate.formula is not smart enough for that.)
-pd
> On 24 Oct 2023, at 14:40 , Sarah Goslee <sarah.goslee at gmail.com> wrote:
>
> Hi,
>
> I think you're misunderstanding which set of variables go on either
> side of the formula.
>
> Is this what you're looking for?
>
>> aggregate(OD ~ Time + Target + Conc, data = df, FUN = "mean")
> Time Target Conc OD
> 1 1 BACT 1 765.3333
> 2 1 BACT 2 745.3333
> 3 1 BACT 3 675.0000
>> aggregate(ODnorm ~ Time + Target + Conc, data = df, FUN = "mean")
> Time Target Conc ODnorm
> 1 1 BACT 1 108.33333
> 2 1 BACT 2 88.33333
> 3 1 BACT 3 18.00000
>
> Or using a different form, that might be more straightforward to you:
>
>> aggregate(df[, c("OD", "ODnorm")], by = df[, c("Time", "Target", "Conc")], data = df, FUN = "mean")
> Time Target Conc OD ODnorm
> 1 1 BACT 1 765.3333 108.33333
> 2 1 BACT 2 745.3333 88.33333
> 3 1 BACT 3 675.0000 18.00000
>
> Sarah
>
> On Tue, Oct 24, 2023 at 8:31?AM Luigi Marongiu <marongiu.luigi at gmail.com> wrote:
>>
>> Hello,
>> I have a data frame with different groups (Time, Target, Conc) and
>> each entry has a triplicate value of the measurements OD and ODnorm.
>> How can I merge the triplicates into a single mean value?
>> I tried the following:
>> ```
>> df = data.frame(Time=rep(1, 9), Well=paste("A", 1:9, sep=""),
>> OD=c(666, 815, 815, 702, 739, 795, 657, 705, 663),
>> Target=rep("BACT", 9),
>> Conc=c(1,1,1,2,2,2,3,3,3),
>> ODnorm=c(9, 158, 158, 45, 82, 138, 0, 48, 6),
>> stringsAsFactors = FALSE)
>> aggregate(.~ODnorm, df, mean)
>>
>>> aggregate(.~ODnorm, df, mean)
>> ODnorm Time Well OD Target Conc
>> 1 0 NA NA NA NA NA
>> 2 6 NA NA NA NA NA
>> 3 9 NA NA NA NA NA
>> 4 45 NA NA NA NA NA
>> 5 48 NA NA NA NA NA
>> 6 82 NA NA NA NA NA
>> 7 138 NA NA NA NA NA
>> 8 158 NA NA NA NA NA
>>
>> aggregate(cbind(Time, Target, Conc) ~ ODnorm, df, mean)
>> ODnorm Time Target Conc
>> 1 0 NA NA NA
>> 2 6 NA NA NA
>> 3 9 NA NA NA
>> 4 45 NA NA NA
>> 5 48 NA NA NA
>> 6 82 NA NA NA
>> 7 138 NA NA NA
>> 8 158 NA NA NA
>> ```
>>
>> Thank you.
>>
>> ______________________________________________
>> R-help at 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.
>
>
>
> --
> Sarah Goslee (she/her)
> http://www.numberwright.com
>
> ______________________________________________
> R-help at 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.
--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com