Problem and Dataset
I recently had a client who wanted a quick way to count the number of unique values in a list. In the following case, the number of unique names in the data in column A.
The general format of the formula is:
How it Works
The trick is in knowing how the formula actually works.
If you evaluate the formula, this is what you get:
- The formula counts the number of instances of each name in the list (7; 7; 7; ….), and stores the count in an array.
- 1/Array creates fractions for each value in the list.
- SUMPRODUCT then sums up the fractions for each name (7*1/7, 2*1/2, etc.) and gives you the number of 1s in the calculation.
Genius, I say!