R aggregate() Syntax Issue - Trying to Count Values

Asked Apr 17 '18 at 19:38

Active Apr 17 '18 at 19:58

Viewed 20 times

I have a data set shaped like the following:

Buyer | Broker | Brand

I am trying to use aggregate to count the number of Buyers by Broker and Brand to quantify market share. It should look like this:

Broker | Brand | Buyer_Count

Acme | Nike | 50

Acme | Reebok | 20

Acme | Converse | 30

Megacorp | Nike | 80

Megacorp | Reebok | 120

...

I am using:

Agg <- aggregate(Buyer ~ Broker + Brand, data = mydata, fun=count)

and it says

"Error in UseMethod("groups") : no applicable method for 'groups' applied to an object of class "character" "

I am pretty sure the issue is "fun = count" not being the correct function but am not sure what the correct function would be here.

I tried match.fun(count) but did not get one that works there either. I also tried google and didn't find anything.

Thank you in advance.

edited Apr 17 '18 at 19:58

Jilber Urbina

asked Apr 17 '18 at 19:38

The_Dza

1

Maybe `FUN=length`? – Jilber Urbina Apr 17 '18 at 19:42
That appears to be working. Can you please explain why you knew to try that? – The_Dza Apr 17 '18 at 19:46
1

It works because `length` returns the number of elements of your object, in this case your object is `Buyer` grouped by `Broker+Brand`, then `length` "counts" how many `Buyers` there are by `Broker+Brand`. – Jilber Urbina Apr 17 '18 at 19:49
Thank you for explaining how it works. I appreciate the additional detail. – The_Dza Apr 17 '18 at 20:16

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