R help - Sep 2012 - a newbie seeking for a simple problem

Dear Experienced R users,

I have a looks-like simple but complicated problem urgently needed to be solved.
Below is the detail:

I have two dataframes, df1, df2. df1 contains two column and many thousands
rows: column 1 is a "gene_name", column 2 is "value". df2
contains only one column which is "gene_name" with couple hundred
rows. I want to change "value" of df2 for those "gene_name"
also appear in df2 "gene_name". How to do that? Millions thanks.


Ste

Read the posting guide... you need to provide more specific information such as
sample data (?dput).

For this problem you should probably read

?merge
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live
Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
--------------------------------------------------------------------------- 
Sent from my phone. Please excuse my brevity.

"Hon Kit (Stephen) Wong" <honkit at stanford.edu> wrote:
>Dear Experienced R users,
>
>I have a looks-like simple but complicated problem urgently needed to
>be solved. Below is the detail:
>
>I have two dataframes, df1, df2. df1 contains two column and many
>thousands rows: column 1 is a "gene_name", column 2 is
"value". df2
>contains only one column which is "gene_name" with couple hundred
rows.
>I want to change "value" of df2 for those "gene_name"
also appear in
>df2 "gene_name". How to do that? Millions thanks.
>
>
>Ste
>
>______________________________________________
>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.

As df2 has only one column and is thus effectively a variable in this case,
you don't even need to merge.

df1[df1$gene_name%in%df2$gene_name , ] 

should do.

HTH,
Daniel


wong, honkit (Stephen) wrote
> 
> Dear Experienced R users,
> 
> I have a looks-like simple but complicated problem urgently needed to be
> solved. Below is the detail:
> 
> I have two dataframes, df1, df2. df1 contains two column and many
> thousands rows: column 1 is a "gene_name", column 2 is
"value". df2
> contains only one column which is "gene_name" with couple hundred
rows. I
> want to change "value" of df2 for those "gene_name"
also appear in df2
> "gene_name". How to do that? Millions thanks.
> 
> 
> Ste
> 
> ______________________________________________
> R-help@ 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.
> 



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