TIL: Moving average with missing periods in Google Sheets

=AVERAGEIFS(A1:A99, B1:B99,"<="&B2, B1:B99, ">"&B2 - 30)

Values to be averaged are in A1:A99, corresponding dates are in B1:B99.

What the formula does: average the values in the range – Include a value in calculating average for the current date if:

1. The date for that value is same as or before the date in the current row, and
2. The date for that value is greator than the date X days before the date in the current row (X is 30 in the formula for a 30-day moving average)

The long one:

I have a spreadsheet with my daily weight log. It has occasional missing days – when I didn’t log my weight.

Yesterday, I wanted to chart this data, and wanted to add a moving average to it. Google sheets’ in-built moving average trend line refused to work – either due to the missing data, or due to the number of entries. So I added a column to the sheet with the calculated (trailing) moving average weight.

I’ve never before had to calculate moving average over a non-consecutive data set. So, in case I forget, I’m noting it down here for later…

TIL: Conditional sum product in Google Sheets

=SUMPRODUCT(D5:D1009="",C5:C1009,B5:B1009)

Just learnt an easy way to do conditional SumProduct1 calculations in Google Sheets2.

In above example, I wanted the SumProduct of values in columns B and C, when the respective cell in column D was empty.

The solution is to simply introduce the conditional column as another input, with the condition stated in the input.

Sheets does the SumProduct calculations, with each true as 1, and false as 0, thus making it a Conditional SumProduct :)