Sum of Distinct Count Variance

user033690 · October 2020

Hi

I need help on below beast mode not working. I am trying to get the sum of all the variance using distinct count of customers. I am trying to get my total points of distribution gained. Thank you in advance.

SUM(COUNT(DISTINCT
CASE WHEN `Year`= 2020 AND `Month #` <=`Month # for Today`
THEN `Customer Name`
END
))
-
SUM(COUNT(DISTINCT
CASE WHEN `Year`= 2019 AND `Month #` <=`Month # for Today`
THEN `Customer Name`
END
))

jaeW_at_Onyx · October 2020

So ... while window functions are amazing for many things, it won't work when you're trying to do a count distinct.

why?

SUM(

COUNT(DISTINCT

CASE WHEN `Year`= YEAR(CURRENT_DATE()) AND `Month #` <=`Month # for Today` THEN `Customer Name`
END
))
OVER ()

keep in mind what is happening under the hood. first Domo does a COUNT(DISTINCT) of customer names, for whatever is on the Axis. (set of items)

then it adds up all the results.

so if i had item 1 = 15 distinct customers, item2 = 12 distinct customers and item3 = 31 distinc customers, i can't just sum 15,12,31... because presumeably i have overlap in the customers who bought items.

SOLUTION

APPEND your data onto itself (UNION) but change the Item number in the second UNION to be a constant 'Total Items'.

now you can do a basic count(distinct customer) and you'll have a 'Total Items' ... item.

GrantSmith · October 2020

Hi @user033690

You might be able to solve your problem using a windowing function however I'd recommend restructuring your data. I've done a previous write up regarding customized period over period data models. You can refer to https://dojo.domo.com/t5/Card-Building/show-percent-on-period-over-period-graph/m-p/50540/highlight/... for an in dept description of what needs to happen.

The basics being you'd have a period type column for Current and Last Year (which you'd filter on just these two) which you can then use a beast mode to calculate the total for that period and then subtract the two numbers. I'd highly recommend this method as it gives you a lot more flexibility in your analysis.

If you must use a beast mode you could try something like:

SUM(COUNT(DISTINCT
CASE WHEN `Year`= YEAR(CURRENT_DATE()) AND `Month #` <=`Month # for Today`
THEN `Customer Name`
END
))
OVER ()
-
SUM(COUNT(DISTINCT
CASE WHEN `Year`= YEAR(CURRENT_DATE())-1 AND `Month #` <=`Month # for Today`
THEN `Customer Name`
END
))
OVER ()

I've also replaced 2020 and 2019 with YEAR(CURRENT_DATE()) functions to automatically calculate the current year and last year (hence the -1) so you don't have to worry about changing the year value next year and in future years. (Unless you specifically want 2020 and 2019 then use those values)

user033690 · October 2020

Thank you for the response Grant.

I tried the BM you suggested. unfortunately it gives me a different result. Please review the table below. I am looking to get the FY20-FY19 variance both by item and as a total. I hope you can help me figuring this out. Thank you in advance.

Item Number	FY20 Customer Count	FY19 Customer Count	BM result	Should be result
1012B	96	84	89	12
1042B	91	83	89	8
1044	90	84	89	6
1022B	80	69	89	11
1014B	67	64	89	3
1092B	58	52	89	6
Total	482	436	534	46

jaeW_at_Onyx · October 2020