Hi Guys，

For the 1st question, I wonder what is the result of r(2,2). Why not “?”?

Thanks!

Best,

Yang

Hi @younghope11

r(i,j) represent if user j has rated movie i or not i=rows , j = columns in this example…if user j has rated movie i so r(i,j) = 1 if not r(i,j) = 0…and so on

please feel free to ask any question,

Thanks,

Abdelrahman

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Hello,

Just adding to the other two correct comments of @SamReiswig and @AbdElRhaman_Fakhry:

Note that the values you are seeing in the table are values for y^{(i,j)} not for r(i,j). The function r(i,j) is defined like in the slide from the comment of @SamReiswig, so r(i,j) is 0 exactly when y^{(i,j)} is “?” and r(i,j) is 1 anytime y^{(i,j)} has an integer value.

I hope that helps!

Best,

Alex

Hi all,

Now I got it! Many thanks for your quick response!

Best,

Yang

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