To calculate the association between Coffee and milk.
Association Rule:
Coffee → Milk
Support: How many out of all rows got both?
Sum of common 1s in Coffee and Milk divided by the sum of all items (0 or 1) in Coffee. 3/6 or 1/2 or 50%..!
Confidence: Of the Coffee buyers how many also got Milk?
Sum of all 1s in Coffee divided by Sum of common 1s in Coffee and Milk . 4/3 or 75%.