[R] Merging dataframes

[Sarmah, Chintanu]

Thanks, Peter, Eivind and Lui

Sorry, I could not explain it properly in the first go. Trying to simplify it here with an example - Say I have two dataframes as below that are not equally-sized data frames:

Table_A:
Email             Name                   Phone
abc at gmail.com<mailto:abc at gmail.com>   John Chan         0909
bcd at yahoo.com<mailto:bcd at yahoo.com>   Tim Ma                    89089
......

Table_B:
Email              Name                 Sex        Phone
abc at gmail.com<mailto:abc at gmail.com>    John Chan        M                 0909
khn at hotmail.com<mailto:khn at hotmail.com>           Rosy  M               F                   7779
.....

Now, I have used -
merge (Table_A, Table_B, by="Email", all = FALSE))

- to find only the rows that match from these data frames.

Further, I am also interested (using "Email" as the common key) which rows from Table_A did not match with Table_B.
I am not sure how to do here.

 Thanks.


On 1 May 2018, at 9:35 pm, Chintanu <chintanu at gmail.com<mailto:chintanu at gmail.com>> wrote:


---------- Forwarded message ----------
From: peter dalgaard <pdalgd at gmail.com<mailto:pdalgd at gmail.com>>
Date: Tue, May 1, 2018 ar-help at r-project.org<mailto:r-help at r-project.org>t 9:05 PM
Subject: Re: [R] Merging dataframes
To: Rui Barradas <ruipbarradas at sapo.pt<mailto:ruipbarradas at sapo.pt>>
Cc: Chintanu <chintanu at gmail.com<mailto:chintanu at gmail.com>>, R help <r-help at r-project.org<mailto:r-help at r-project.org>>


I'd expect more like

setdiff(A$key, B$key)

and vice versa. Or, if you want the actual rows

A[!(A$key %in% B$key),]

or for the row numbers

which(!(A$key %in% B$key))


-pd




> On 1 May 2018, at 12:48 , Rui Barradas <ruipbarradas at sapo.pt<mailto:ruipbarradas at sapo.pt>> wrote:
>
> Hello,
>
> Is it something like this that you want?
>
> x <- data.frame(a = c(1:3, 5, 5:10), b = c(1:7, 7, 9:10))
> y <- data.frame(a = 1:10, b = 1:10)
>
> which(x != y, arr.ind = TRUE)
>
>
> Hope this helps,
>
> Rui Barradas
>
> On 5/1/2018 11:35 AM, Chintanu wrote:
>> Hi,
>> May I please ask how I do the following in R. Sorry - this may be trivial,
>> but I am struggling here for this.
>> For two dataframes (A and B), I wish to identify (based on a primary
>> key-column present in both A & B) -
>> 1. Which records (rows) of A did not match with B, and
>> 2. Which records of B did not match with A ?
>> I came across a setdt function while browsing, but when I tried it, it says
>> - Could not find function "setdt".
>> Overall, if there is any way of doing it (preferably in some simplified
>> way), please advise.
>> Many thanks in advance.
>> regards,
>> Tito
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Office: A 4.23
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