[R] merging or joining 2 dataframes: merge, rbind.fill, etc.?

[David L Carlson]

Clumsy but it doesn't require any packages:

merge2 <- function(x, y) {
if(all(union(names(x), names(y)) == intersect(names(x), names(y)))){
    rbind(x, y)
    } else merge(x, y, all=TRUE)
}
merge2(df1, df2)
df3 <- df1
merge2(df1, df3)

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352




> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of arun
> Sent: Tuesday, February 26, 2013 1:14 PM
> To: Anika Masters
> Cc: R help
> Subject: Re: [R] merging or joining 2 dataframes: merge, rbind.fill,
> etc.?
> 
> Hi,
> 
> You could also try:
> library(gtools)
> smartbind(df2,df1)
> #  a  b  d
> #1 7 99 12
> #2 7 99 12
> 
> 
> When df1!=df2
> smartbind(df1,df2)
> #   a  b  d  x  y  c
> #1  7 99 12 NA NA NA
> #2 NA 34 88 12 44 56
> A.K.
> 
> 
> 
> 
> ----- Original Message -----
> From: Anika Masters <anika.masters at gmail.com>
> To: r-help at r-project.org
> Cc:
> Sent: Tuesday, February 26, 2013 1:55 PM
> Subject: [R] merging or joining 2 dataframes: merge, rbind.fill, etc.?
> 
> #I want to "merge" or "join" 2 dataframes (df1 & df2) into a 3rd
> (mydf).  I want the 3rd dataframe to contain 1 row for each row in df1
> & df2, and all the columns in both df1 & df2. The solution should
> "work" even if the 2 dataframes are identical, and even if the 2
> dataframes do not have the same column names.  The rbind.fill function
> seems to work.  For learning purposes, are there other "good" ways to
> solve this problem, using merge or other functions other than
> rbind.fill?
> 
> #e.g. These 3 examples all seem to "work" correctly and as I hoped:
> 
> df1 <- data.frame(matrix(data=c(7, 99, 12) ,  nrow=1 ,  dimnames =
> list( NULL ,  c('a' , 'b' , 'd') ) ) )
> df2 <- data.frame(matrix(data=c(88, 34, 12, 44, 56) ,  nrow=1 ,
> dimnames = list( NULL ,  c('d' , 'b' , 'x' ,  'y', 'c') ) ) )
> mydf <- merge(df2, df1, all.y=T, all.x=T)
> mydf
> 
> #e.g. this works:
> library(reshape)
> mydf <- rbind.fill(df1, df2)
> mydf
> 
> #This works:
> library(reshape)
> mydf <- rbind.fill(df1, df2)
> mydf
> 
> #But this does not (the 2 dataframes are identical)
> df1 <- data.frame(matrix(data=c(7, 99, 12) ,  nrow=1 ,  dimnames =
> list( NULL ,  c('a' , 'b' , 'd') ) ) )
> df2 <- df1
> mydf <- merge(df2, df1, all.y=T, all.x=T)
> mydf
> 
> #Any way to get "mere" to work for this final example? Any other good
> solutions?
> 
> ______________________________________________
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> 
> ______________________________________________
> 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.