[R] create new column to combine 2 data.frames

[arun]

Hi,

You can use 'fill=0' in ?cast()
merge(dat1,cast(melt(dat2, c("ID", "Type")), ID~Type,fill=0))
#  ID Name Management Training
#1  1 Jack          1        3
#2  2 John          1        0
#3  3 Jill          0        4
A.K.



----- Original Message -----
From: PIKAL Petr <petr.pikal at precheza.cz>
To: Mat <matthias.weber at fnt.de>; "r-help at r-project.org" <r-help at r-project.org>
Cc: 
Sent: Friday, August 30, 2013 5:57 AM
Subject: Re: [R] create new column to combine 2 data.frames

Hi

Sorry, I did not read your question to the end

library(reshape)

merge(dat1,cast(melt(dat2, c("ID", "Type")), ID~Type))
  ID Name Management Training
1  1 Jack          1        3
2  2 John          1       NA
3  3 Jill         NA        4

Is close enough, you can easily change NA to 0 if you want.

Regards
Petr

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Mat
> Sent: Friday, August 30, 2013 11:27 AM
> To: r-help at r-project.org
> Subject: Re: [R] create new column to combine 2 data.frames
> 
> Thanks first.
> 
> that doesn't look bad. But if have a equal ID in dat2, the days are no
> longer correct.
> 
> the correct data.frame has to look like this one:
> 
>   ID Name Management Training
> 1  1 Jack          1        3
> 2  2 John          1        0
> 3  3 Jill          0        4
> 
> not this one:
> 
>   ID Name Management Training
> 1  1 Jack          1        1
> 2  2 John          3        0
> 3  3 Jill          0        1
> 
> > dat1 <- read.table(text = "
> + ID Name
> + 1  Jack
> + 2  John
> + 3  Jill
> + ", header = TRUE, stringsAsFactors = FALSE)
> >
> > dat2 <- read.table(text = "
> + ID  Days  Type
> + 1    1       Management
> + 1    3       Training
> + 2    1       Management
> + 3    4       Training
> + ", header = TRUE, stringsAsFactors = FALSE)
> >
> > library(reshape2)
> > tmp <- dcast(data = dat2, ID ~ Type, value.var = "Type")
> >
> > tmp[-1] <- lapply(tmp[-1], function(x){
> + y <- integer(length(x))
> + y[!is.na(x)] <- dat2[["Days"]][!is.na(x)]
> + y})
> > result <- merge(dat1, tmp)
> > result
>   ID Name Management Training
> 1  1 Jack          1        1
> 2  2 John          3        0
> 3  3 Jill          0        1
> >
> 
> 
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/create-new-
> column-to-combine-2-data-frames-tp4674963p4674968.html
> Sent from the R help mailing list archive at Nabble.com.
> 
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