Thank you. Yes, lines 1-4 should have answers as well, but I only included 1 month and the dates early in the month will not have prior dates to sum. For the ouput, I would like to include all the columns that are listed for each observation (ID, var1, var2, dt, sum_to_date) as well as the summation of var1 and var2. Would the monotonic function help to uniquely identify each row? Yes, the end of the interval would be include in the sum. So the observation/row would be possibly summing 3 numbers if there is a date that is within 2 days prior to the date on the observation/row.
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