Knowledge Drop

# How do I use custom filters to get a YoY of the last X complete days within the same month?

• Looker Staff
• 4 replies

Last tested: Apr 23, 2019

Use this awesome filter:

`(extract_months(\${date}) = extract_months(now())) AND extract_days((\${date})) <= extract_days(now())-1ANDextract_days((\${date})) >= extract_days(now())-xAND(extract_years(\${sources.date_date}) = (extract_years(now()))OR extract_years(\${sources.date_date}) = (extract_years(now())-1))`

We'd want to replace the "x" at the end of `extract_days((\${date})) >= extract_days(now())-x` with the number of days you want. For example, if we want a YoY for the last 5 complete days, we'd replace the `x` with `5`.

Note: This will only work if we're trying to select days from the same month. This calc relies on the extract_days function and subtraction. So for example if it's May 2nd and we want the last 30 days, the filter won't work.

This is because `extract_days((\${date})) >= extract_days(now())-30` would yield:
-28, -27, -26, ..., 0, 1 and 5/-28 isn't a date.

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