[R] Dataframe: Average cells of two rows and replace them with one row

[PIKAL Petr]

Hi

AFAIK you can not average values only in 2 columns leaving others intact. The exact code depends on what are in columns 2-39 in your data frame. If numbers, you can averege them as well.

Something like

dat.ag <- aggregate(dat[,-1], list(dat$Name), mean, na.rm=TRUE)

if your data frame is named dat and first column calls Name. You get new object with aggregated values for the same Name.

If some columns are nonnumeric the problem gets trickier and solution strongly depends what mode are those columns and what you want to do with them when aggregating values in column 40 and 41.

Show us at least structure of your data frame.

?str

Regards
Petr

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Verena Weinbir
> Sent: Wednesday, May 28, 2014 2:00 PM
> To: arun
> Cc: r-help
> Subject: Re: [R] Dataframe: Average cells of two rows and replace them
> with one row
>
> Hey guys,
>
> thank you very much for your help.  Since I am a R-newbie I am still
> checking out how your code works and how I could adapt it to my
> dataframe,
> which has 124 rows and 41 columns/variables.  The first column would be
> "name", the last ones, 40 and 41, contain the cells I want to average
> for
> some rows. Is it possible to read the dataframe without copying the
> whole
> thing into the text"" function (just tried it and got an error
> message)?
>
> Thank you!
>
> Verena
>
>
> On Wed, May 28, 2014 at 3:48 AM, arun <smartpink111 at yahoo.com> wrote:
>
> > Hi,
> > You can also try:
> > dat <- read.table(text="Name C1 C2 C3
> >   1  A  3  3  5
> >   2  B  2  7  4
> >   3  C  4  3  3
> >   4  C  4  4  6
> >   5  D  5  5  3",sep="",header=TRUE,stringsAsFactors=FALSE)
> >
> >
> >  library(plyr)
> >  ddply(dat,.(Name),numcolwise(mean,na.rm=TRUE))
> > A.K.
> >
> >
> > On Tuesday, May 27, 2014 4:08 PM, Verena Weinbir <vweinbir at gmail.com>
> > wrote:
> > Hello,
> >
> > I have a big dataframe, and want to average two specific cells of two
> > specific rows and then replace those two rows with one row which
> contains
> > the averaged cells. Example (row 3 and 4: Cells2 and Cells3 averaged
> and
> > replaced)
> >
> >     NameC1 C2 C3
> >   1  A  3  3  5
> >   2  B  2  7  4
> >   3  C  4  3  3
> >   4  C  4  4  6
> >   5  D  5  5  3
> >
> >
> >
> >     NameC1 C2  C3
> >   1  A  3  3   5
> >   2  B  2  7   4
> >   3  C  4  3.5 4.5  4  D  5  5   3
> >
> >
> > Many thanks in advance!
> >
> > Best,
> >
> > Verena
> >
> >     [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help at r-project.org mailing list
> > 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.
> >
>
>       [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.

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