Sure!
Let's go through this piece by piece:
if [Row-1:Week]=null() then 1 elseif tonumber([Row-1:Week])=tonumber([Week])-1 then [Row-1:in-a-row]+1 else [Row-1:in-a-row] endif
[Row-1:week] is the row prior to the current week - it looks to see if it doesn't exist. This would be true for the very first row and it also would be true for EVERY row which starts a new grouping - since we grouped on customer. This means that even if customer name pops up again later in the list - it'll still populate at 1. The group option also means that our numbers won't continue if a different customer went to the store the following week.
1 sets the value.
tonumber() converts to number from string
[row-1:week]=[week]-1 says are these in a row. Ie is the value for week in the previous row one less than the current value. If so - then we'll add 1 to the previous value (ie the number of weeks in a row a customer visited the store).
else [row-1:in-a-row] this tells atleryx to look at the previous entries value here and just carry it over. It's kind of as close to recursion at Alteryx gets.
ENDIF. in alteryx you need to conclude an if statement with endif OR IT WILL NOT WORK. The three most common errors on If statements
1) comparing unlike types (ie strings and integers)
2) not including endif
3) not including else statements.
unlike Excel and many programming languages - Alteryx requires all If statements to have elses and endifs at the conclusion of the statment.
