[R] merging several dataframes from a list

[Antje]

Henrique Dallazuanna schrieb:
> Try this also:
> 
>  cbind(pos = mylist$df1$pos, data.frame(mylist)[grep("data", 
> names(data.frame(mylist)))])

Hi Henrique,

cool solution - that's seems to be the easiest way!
though I thought there should be some possibiliy of multiple merge

Anyway, this will do it for now!

Thank you!


> 
> On Wed, Jan 21, 2009 at 6:19 AM, Antje <niederlein-rstat at yahoo.de 
> <mailto:niederlein-rstat at yahoo.de>> wrote:
> 
>     Hi there,
> 
>     I have a list of dataframes (generated by reading multiple files)
>     and all dataframes are comparable in dimension and column names.
>     They also have a common column, which, I'd like to use for merging.
>     To give a simple example of what I have:
> 
>     df1 <- data.frame(c(LETTERS[1:5]), c(2,6,3,1,9))
>     names(df1) <- c("pos", "data")
>     df3 <- df2 <- df1
>     df2$data <- c(6,2,9,7,5)
>     df3$data <- c(9,3,6,2,1)
>     mylist <- list(df1,df2,df3)
>     names(mylist) <- c("df1","df2","df3")
> 
>      > mylist
> 
>     $df1
>      pos data
>     1   A    2
>     2   B    6
>     3   C    3
>     4   D    1
>     5   E    9
> 
>     $df2
>      pos data
>     1   A    6
>     2   B    2
>     3   C    9
>     4   D    7
>     5   E    5
> 
>     $df3
>      pos data
>     1   A    9
>     2   B    3
>     3   C    6
>     4   D    2
>     5   E    1
> 
>     If I use do.call("cbind"), I'll end up with something like this
> 
>       pos data pos data pos data
>     1   A    2   A    6   A    9
>     2   B    6   B    2   B    3
>     3   C    3   C    9   C    6
>     4   D    1   D    7   D    2
>     5   E    9   E    5   E    1
> 
> 
>     but now, I don't know anymore which data comes from which
>     dataframe... and I have the column "pos" multiple times...
> 
>     Instead I'd like to have it like this:
> 
>       pos df1 df2 df3
>     1   A    2   6   9
>     2   B    6   2   3
>     3   C    3   9   6
>     4   D    1   7   2
>     5   E    9   5   1
> 
>     How, can I realize it? (The list, I'm working with has not just 3
>     data frames like given in my example, so I need to automize it)
> 
> 
>     Antje
> 
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> 
> 
> 
> 
> -- 
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O