Count numbers for occurrences

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Panayiotis Christodoulou
编辑： the cyclist 2016-5-18
Hi there,
I have a table
UserID, Market, Geo, Price, Product
I want to count for each userID how many times he bought product = 1 and how many times product=2
Final Dataset UserID, Product1, Product2
Thanks, Pan

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Sebastian Castro
Sebastian Castro 2016-5-16
编辑：Sebastian Castro 2016-5-16
I'm guessing at your variable names and their format... but assuming that UserID and Product are both numeric variables, you can use the nnz (number of nonzero) function to get a count.
For example, say you want the number of Product 2 that UserID 6 purchased:
count = nnz( (myTable.UserID == 6) & (myTable.Product == 2) )
You can, of course, extend this to different user IDs and product numbers as you see fit. I'd make this into a function:
function count = getProdCount(t,uid,prod)
% t = Table
% uid = User ID
% prod = Product number
count = nnz( (t.UserID == uid) & (t.Product == prod) );
end
Then you can call it as follows:
count = getProdCount(myTable,6,2)
- Sebastian
  1 个评论
Panayiotis Christodoulou
Panayiotis Christodoulou 2016-5-18
i created my own code based on my data using the first sentence
count = nnz( (myTable.UserID == 6) & (myTable.Product == 2) )
thanks

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更多回答（2 个）

Duncan Po
Duncan Po 2016-5-17
If you are using R2015b or later versions, you can use findgroups and splitapply:
% Set up a table with pretend data
userid = [1; 1; 1; 1; 1; 2; 2; 2; 2; 2; 2; 3];
product = [1; 1; 2; 3; 3; 1; 2; 2; 2; 2; 2; 3];
T = table(userid,product);
% split into groups and compute counts
[g, T2] = findgroups(T);
T2.count = splitapply(@numel,T,g);
% trim the table
T2 = T2(ismember(T2.product,[1 2]),:)
the cyclist
the cyclist 2016-5-16
Here is one way, generally using table functions to do everything.
% Set up a table with pretend data
userid = [1; 1; 1; 1; 1; 2; 2; 2; 2; 2; 2; 3];
product = [1; 1; 2; 3; 3; 1; 2; 2; 2; 2; 2; 3];
T = table(userid,product);
% Find counts where product = 1 (and rename the resulting variable)
T1 = varfun(@(x)sum(x==1),T,'InputVariables','product','GroupingVariables','userid');
T1.Properties.VariableNames{'Fun_product'} = 'Product1'
% Find counts where product = 2 (and rename the resulting variable)
T2 = varfun(@(x)sum(x==2),T,'InputVariables','product','GroupingVariables','userid');
T2.Properties.VariableNames{'Fun_product'} = 'Product2'
% Join the results
T12 = join(T1,T2)

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