Measure for previous year date

[amaaiia]

Hi!

I want a measure to compare one time range sales with previous year same time range sales. For example:

If selected time range A (for a given alt_state)--> 2020-09-01 to 2020-09-30, I need a measure like this:

sum({alt_state} sales)-sum({alt_state <date={'$(=AddYears(date,-1))'}>} sales)

(this doesn't work)

So I can get this:

date	AddYears(date,-1)	sales	previous sales	diff
2020-09-01	2019-09-01	100	95	5
2020-09-02	2019-09-02	120	130	-10
...	...	...	...	...

or even this:

month(date)	month(AddYears(date,-1))	sales	previous sales	diff
sept-2020	sept-2019	3000	2500	500
oct-2020	oct-2019	3250	3300	-50
..	...	...	...	...

or a bar chart where Dimension = month(date) and Measure is the diff for alt_state month vs previous year, with only the days selected (if from 2nd to 15th of sept selected, month(date) would be sept-2020 but just with information from 2nd to 15th sept)

Thanks!

[hic]

I would define a field in the script for this, e.g.

   Date - YearStart(Date) as DayWithinYear,

You can even format it as month+day:

   Date(Date - YearStart(Date) + 2,'MMM DD') as DayWithinYear,

If you then make a chart with Year as dimension, and make a selection in DayWithinYear, then you have what you want.