Bar Charts and Set expressions

[#1]

All,

I think I am likely missing something simple here, but I a stumped.  I am working with some product usage data that looks basically like:

Month	AccountID	Usage
1/1/2015	123	50
1/1/2015	456	75
2/1/2015	123	60
2/1/2015	456	100
etc

What I want to do is create a bar chart that shows the Growth in usage each month using 1/1/2015 as the baseline.  So essentially 1/1/2015 would have a value of 0 and 2/1/2015 would have a value of 35(60-50 and 100-75)

I thought I could use something like:

Dimension - Month.autocalendar.YearMonth

Measure - Sum(Usage) - Sum ({$<Month = {'1/1/2015'}>}Usage)

But this just takes the January 2015 value to 0 and does not change any of the other months.

Any suggestions?

[sunny_talwar]

Try this:

Sum(Usage) - Sum (TOTAL {$<Month = {'1/1/2015'}>}Usage)

[sunny_talwar · Accepted solution]

My bad, you need this:

Sum(Usage) - Sum (TOTAL <AccountID> {$<Month = {'1/1/2015'}>}Usage)