Dynamic OVER(PARTITION BY) DAX Equivalent

// Total number of visits
[# Visits] = SUM( T[Visits Number] )

// Returns the bucket for the
// total number of visits;
// you might need to adjust the
// limits in the disconnected
// Buckets table (500 might not
// be enough).
[Visit Bucket] =
var __visitCount = [# Visits]
return
	CALCULATE(
		SELECTEDVALUE( Buckets[Bucket] ),
		Buckets[Min] <= __visitCount,
		__visitCount <= Buckets[Max],
		ALL( Buckets )
	)

// For any slicing, it shows you
// the number of customers that fall
// into a selected bucket.
[# Customers in Bucket] =
var __currentBucket =
	SELECTEDVALUE( Buckets[Bucket] )
var __output =
	SUMX(
		VALUES( T[Customer ID] ),
		1 * ( [Visit Bucket] = __currentBucket )
	)
return
	if( __output > 0, __output )