count until value changes (in diagram)

[#1]

hello and a happy new year to everyone

i've got a question about a counting function:

how can i count the rows until the value in one column changes.

ex:

A

A

A

A

A

A

B

B

B

A

A

A

A

i want to count all "A's" before the value changes to "B"

thx for your help!

[MarcoWedel]

Thanks.

Glad you liked it.

Another solution might be:

Count(Distinct ClusterNum)

regards

Marco