# [R] counting duplicate items that occur in multiple groups

Tom Woolman twoo|m@n @end|ng |rom ont@rgettek@com
Wed Nov 18 00:29:39 CET 2020

```Hi Bill. Sorry to be so obtuse with the example data, I was trying
(too hard) not to share any actual values so I just created randomized
values for my example; of course I should have specified that the
random values would not provide the expected problem pattern. I should
have just used simple dummy codes as Bill Dunlap did.

So per Bill's example data for Data1, the expected (hoped for) output
should be:

Vendor Account Num_Vendors_Sharing_Bank_Acct
1     V1      A1      0
2     V2      A2      3
3     V3      A2      3
4     V4      A2      3

Where the new calculated variable is Num_Vendors_Sharing_Bank_Acct.
The value is 3 for V2, V3 and V4 because they each share bank account
A2.

Likewise, in the Data2 frame, the same logic applies:

Vendor Account Num_Vendors_Sharing_Bank_Acct
1     V1      A1     0
2     V2      A2     3
3     V3      A2     3
4     V1      A2     3
5     V4      A3     0
6     V2      A4     0

Thanks!

Quoting Bill Dunlap <williamwdunlap using gmail.com>:

> What should the result be for
>   Data1 <- data.frame(Vendor=c("V1","V2","V3","V4"),
> Account=c("A1","A2","A2","A2"))
> ?
>
> Must each vendor have only one account?  If not, what should the result be
> for
>    Data2 <- data.frame(Vendor=c("V1","V2","V3","V1","V4","V2"),
> Account=c("A1","A2","A2","A2","A3","A4"))
> ?
>
> -Bill
>
> On Tue, Nov 17, 2020 at 1:20 PM Tom Woolman <twoolman using ontargettek.com>
> wrote:
>
>> Hi everyone.  I have a dataframe that is a collection of Vendor IDs
>> plus a bank account number for each vendor. I'm trying to find a way
>> to count the number of duplicate bank accounts that occur in more than
>> one unique Vendor_ID, and then assign the count value for each row in
>> the dataframe in a new variable.
>>
>> I can do a count of bank accounts that occur within the same vendor
>> using dplyr and group_by and count, but I can't figure out a way to
>> count duplicates among multiple Vendor_IDs.
>>
>>
>> Dataframe example code:
>>
>>
>> #Create a sample data frame:
>>
>> set.seed(1)
>>
>> Data <- data.frame(Vendor_ID = sample(1:10000), Bank_Account_ID =
>> sample(1:10000))
>>
>>
>>
>>
>> Thanks in advance for any help.
>>
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