[R] Aggregate over multiple and unequal column length data frames

[Bert Gunter]

Then you need to rethink your data structure. Use a list instead of a data
frame. The components of a list can have different lengths, and the "apply"
family of functions (lapply(), etc.) can operate on them. Consult any good
R tutorial for details.

Cheers,
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 Tue, Feb 27, 2018 at 5:54 AM, Ek Esawi <esawiek at gmail.com> wrote:

> Thank you Pikal and Bert. My apology for posting parts of my previous
> email in HTML. Bert's suggestion will work but i am wondering if there
> is an alternative
> especially in the case where the data frames are big; that is the
> difference in lengths among them is large. Below is a list of sample
> date frames and desired result.
>
> EK
>
>
> dput(df1<-data.frame(col1=c(1,2,3,4,5),col2=c("aa","aa","bb","cc","dd")))
> dput(df2<-data.frame(col1=c(1,2,4,5),col2=c("bb","bb","cc","bb")))
> dput(df3<-data.frame(col1=c(1,3),col2=c("aa","aa")))
> # desired result
> dput(dfn<-data.frame(col1=c(2,2,1,1),col2=c(0,3,1,0),col3=c(
> 2,0,0,0),row.names
> = c("aa","bb","cc","dd")))
>
> On Fri, Feb 23, 2018 at 7:45 AM, PIKAL Petr <petr.pikal at precheza.cz>
> wrote:
> > Hi
> >
> > Your example is rather confusing - partly because HTML formating, partly
> because weird coding.
> >
> > You probably could concatenate your data frames e.g. by rbind or merge
> and after that you could try to aggregate them somehow.
> >
> > I could construct example data.frames myself but most probably they
> would be different from yours and also the result would not be necessary
> the same as you expect.
> >
> > You should post those data frames as output from dput(data) and show us
> real desired result from those example data frames.
> >
> > Cheers
> > Petr
> >
> >> -----Original Message-----
> >> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Ek
> Esawi
> >> Sent: Wednesday, February 21, 2018 3:34 AM
> >> To: r-help at r-project.org
> >> Subject: [R] Aggregate over multiple and unequal column length data
> frames
> >>
> >>  Hi All--
> >>
> >> I have generated several 2 column data frames with variable length. The
> data
> >> frames have the same column names and variable types. I was trying to
> >> aggregate over the 2nd column for all the date frames, but could not
> figure out
> >> how.
> >>
> >> I thought i could make them all of equal length then combine them in 1
> data
> >> frame where i can use aggregate, the formula version Or to put them in
> a list
> >> and loop use lapply but did not know how to do that and thought there
> might
> >> be a simpler way.
> >>
> >> Below is an example of 3 data frames and the desired result; note that
> some
> >> levels don't appear in all and may be null over all variable, like the
> case of dd
> >> on the desired result which i would like to list all levels even if
> some are all null.
> >>
> >> Thanks in advance,
> >>
> >> EK
> >>
> >>    df1           df2          df3
> >>
> >> c1 c2 c1 c2 c1 c2
> >> 1 aa 1 bb 1 aa
> >> 2 aa 2 bb 2 aa
> >> 3 bb 3 cc
> >> 4 cc 4 bb
> >> 5 bb
> >>
> >> desired result
> >>
> >> c1 c2 c2 c2
> >> aa 2 2
> >> bb 1 2 2
> >> cc 1 1
> >> dd
> >>
> >> [[alternative HTML version deleted]]
> >>
> >> ______________________________________________
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