R help - Oct 2011 - Merge two data frames and find common values and non-matching values

Hi,

I am trying to find a function to match two data frames of different lengths
for one field only.
So, for example,
df1 is:

Name Position location
francesca A 75
cristina B 36

And df2 is:

location Country
75 UK
56 Austria

And I would like to match on "Location" and the output to be something
like:

Name Position Location Match
francesca A 75 1
cristina B 36 0

I have tried with the function 'match' or with:
subset(df1, location %in% df2)
But it does not work.

Could you please help me figure out how to do this?

Thank you!
-f


--
View this message in context:
http://r.789695.n4.nabble.com/Merge-two-data-frames-and-find-common-values-and-non-matching-values-tp3868299p3868299.html
Sent from the R help mailing list archive at Nabble.com.
	[[alternative HTML version deleted]]

Start out with merge():
  > df <- merge(df1, df2, all.x=TRUE) # could add by="location"
for emphasis
  > df
    location      Name Position Country
  1       36  cristina        B    <NA>
  2       75 francesca        A      UK
You could make make your 'Match' column from is.na(df$Country) if you 
knew that df2$Country were never NA.  Otherwise you can add a fake
variable to the merge to tell which output rows come from unmatched
rows in the first data.frame:

  > df12 <- merge(df1, cbind(df2, fromDF2=TRUE), all.x=TRUE,
by="location")
  > df12$Match <- !is.na(df12$fromDF2)
  > df12
    location      Name Position Country fromDF2 Match
  1       36  cristina        B    <NA>      NA FALSE
  2       75 francesca        A      UK    TRUE  TRUE

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf Of francy
> Sent: Monday, October 03, 2011 10:55 AM
> To: r-help at r-project.org
> Subject: [R] Merge two data frames and find common values and non-matching
values
> 
> Hi,
> 
> I am trying to find a function to match two data frames of different
lengths
> for one field only.
> So, for example,
> df1 is:
> 
> Name Position location
> francesca A 75
> cristina B 36
> 
> And df2 is:
> 
> location Country
> 75 UK
> 56 Austria
> 
> And I would like to match on "Location" and the output to be
something like:
> 
> Name Position Location Match
> francesca A 75 1
> cristina B 36 0
> 
> I have tried with the function 'match' or with:
> subset(df1, location %in% df2)
> But it does not work.
> 
> Could you please help me figure out how to do this?
> 
> Thank you!
> -f
> 
> 
> --
> View this message in context:
http://r.789695.n4.nabble.com/Merge-two-data-frames-and-find-common-
> values-and-non-matching-values-tp3868299p3868299.html
> Sent from the R help mailing list archive at Nabble.com.
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.

Hi,


On Mon, Oct 3, 2011 at 1:54 PM, francy <francy.casalino at gmail.com>
wrote:
> Hi,
>
> I am trying to find a function to match two data frames of different
lengths
> for one field only.
> So, for example,
> df1 is:
>
> Name Position location
> francesca A 75
> cristina B 36
>
> And df2 is:
>
> location Country
> 75 UK
> 56 Austria
>
> And I would like to match on "Location" and the output to be
something like:

Sounds like you need merge() (just as in your subject line!).
> Name Position Location Match
> francesca A 75 1
> cristina B 36 0
>
> I have tried with the function 'match' or with:
> subset(df1, location %in% df2)
> But it does not work.
>
> Could you please help me figure out how to do this?
>
Sarah

-- 
Sarah Goslee
http://www.functionaldiversity.org