Preference aggr

[tanjavarwijk1]

How do I get the result:

for each customer the preference city for each color by counting orders

I have tried

Only({$<Color = {"=rank(count( SalesNum),4)=1 "}>}Color)

and

aggr(MaxString(City),Color,CustomerNum)

[brunobertels]

hi 

may be with firstsortedvalue function : 

firstsortedvalue( City, -aggr(MaxString(City),Color,CustomerNum))