# [R] Problem with combining 2 data frame

David L Carlson dc@r|@on @end|ng |rom t@mu@edu
Sun Feb 17 01:49:21 CET 2019

```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

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
> M.Sc. Environment Engineering
> Alternative Mail: bayat194 using yahoo.com
>
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>
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>

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