Merge two data frames and find common values and non-matching values

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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

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Hi,
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
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