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

[Bert Gunter]

All columns in a data.frame **must** have the same length. So you cannot do
this unless empty values are filled with missings (NA's).

-- 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 20, 2018 at 6:33 PM, Ek Esawi <esawiek at gmail.com> wrote:

>  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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