[R] Problem with combining 2 data frame

[PIKAL Petr]

Hi

and if you consider stringsAsFactor option a nuisance you probably could use as.character

df1$x2[match(df2$x1, df1$x1)] <- as.character(df2$x2)

Slightly different approach is merge
merge(df1, df2, by=c("x1"), all=T)

which gives you additional column from df2 with NA values together with merged x2 values.

Cheers
Petr

> -----Original Message-----
> From: R-help <r-help-bounces using r-project.org> On Behalf Of David L Carlson
> Sent: Sunday, February 17, 2019 1:49 AM
> To: Eric Berger <ericjberger using gmail.com>; javad bayat
> <j.bayat194 using gmail.com>
> Cc: R mailing list <R-help using r-project.org>; r-help-owner using r-project.org
> Subject: Re: [R] Problem with combining 2 data frame
>
> This is another approach using match():
>
> df1 = data.frame(x1 = letters[1:26],x2 = NA, stringsAsFactors=FALSE)
> df2 = data.frame(x1 = letters[10:15],x2 = c("1a","2a","3a","4a","5a","6a"),
>      stringsAsFactors =FALSE)
>
> df1$x2[match(df2$x1, df1$x1)] <- df2$x2
>
> ---------------------------------------------
> David L. Carlson
> Department of Anthropology
> Texas A&M University
>
> -----Original Message-----
> From: R-help [mailto:r-help-bounces using r-project.org] On Behalf Of Eric Berger
> Sent: Friday, February 15, 2019 11:43 PM
> To: javad bayat <j.bayat194 using gmail.com>
> Cc: R mailing list <R-help using r-project.org>; r-help-owner using r-project.org
> Subject: Re: [R] Problem with combining 2 data frame
>
> Hi Javad,
> You have a number of problems with your code, such as:
> 1. you should set df1 and df2 without factors 2. you define a function f(x,y) but
> the body of the function never refers to x and y
>
> The following code does what I think you are looking for:
>
> df1 = data.frame(x1 = letters[1:26],x2 = NA,stringsAsFactors = FALSE)
> df2 = data.frame(x1 = letters[10:15],x2 = c("1a","2a","3a","4a","5a","6a"),
> stringsAsFactors = FALSE)
>
> aa <- sapply( 1:nrow(df2), function(i) { df1$x2[ df1$x1==df2$x1[i] ] <<-
> df2$x2[i] } )
>
> HTH,
> Eric
>
>
> On Sat, Feb 16, 2019 at 4:11 AM javad bayat <j.bayat194 using gmail.com> wrote:
>
> > Dear R users;
> > I am trying to combine 2 dataframes with different rows, 26 and 6
> > rows. The first column of both dataframe has something in common, and
> > I want to compare the first column of the df1 with first column of the
> > df2 to see if they are same or not. Then if they were same, the second
> > column of the df1 fill by the value of the second column of df2.
> >
> > df1 = data.frame(x1 = letters[1:26],x2 = NA)
> > df2 = data.frame(x1 = letters[10:15],x2 =
> > c("1a","2a","3a","4a","5a","6a"))
> >
> > f = function(x,y){
> >           for (i in 1:nrow(df1))
> >            ifelse(df1$x1 == df2$x1, df1$x2==df2$x2, "NA")}
> > f(df1,df2)
> > Error in Ops.factor(df1$x1, df2$x1) : level sets of factors are
> > different
> >
> > Is there anyone to help me to solve this problem?
> > Sincerely.
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > --
> > Best Regards
> > Javad Bayat
> > M.Sc. Environment Engineering
> > Alternative Mail: bayat194 using yahoo.com
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
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