In a table calculation, how do I fill all of the null values of a column with the last non-null value of that column before the current row? (Community)

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Last Tested: Jan 21, 2019

index(${calculation_1}, max(offset_list(if(is_null(${calculation_1}), null, row()), -1 * row() + 1, row())))

There are a few steps in this formula:

Get the row number for each non-null row using the row() function
Use offset_list to get a list of all of those row numbers from the first row to the current row
Take the max of that list of values, which will be the row number of the last non-null row
Use the index function to get the value of the field for that row number

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