I couldn't come up with a single formula that would do this so I guess
you'll need to use helper column *and* concatenate your data (unless someone
else can do it without the use of a helper column).

Let's assume the concatenated data is in the range A2:A12

Leave B2 empty

Enter this formula in B3 and copy down to B12:

=IF(OR(AND(A2="ac",A3="bd"),AND(A3=A2,B2<"")),1," ")

That'll identify the cells to count.

D2:Dn = 1,2,3,4,5 etc

Enter this array formula** in E2 and copy down as needed:

=SUM(--(FREQUENCY(IF(B$2:B$12=1,ROW(B$2:B$12)),IF(B$2:B$1 2<1,ROW(B$2:B$12)))=D2))

** array formulas need to be entered using the key combination of
CTRL,SHIFT,ENTER (not just ENTER). Hold down both the CTRL key and the SHIFT
key then hit ENTER.

--
Biff
Microsoft Excel MVP


"Demosthenes" wrote in message
...
The data is in two columns, but would be easy enough to concatenate it.

I spent quite a while trying to figure this out, without any success.

Thanks,

"T. Valko" wrote:

Yes, I saw that post.

A C
B D
B D
B E

Is this data in one or two columns?

It will be *extremely* complicated to do this with a single formula if it
can be done at all.

--
Biff
Microsoft Excel MVP


"Demosthenes" wrote in message
...
Hi Mr. Valko,

You answered my question earlier this week on an Excel '07 discussion
board, and your answer was by far the best and most elegant. Mine was
the question about counting cells in a series, and you answered with a
sum over a frequency. If you don't mind, I have another question
that's based off an elaboration of my first one. Say you have the
following data:

A C
B D
B D
B E
A C
B E
A E
B D
B E
A C
B D

And you want to count how many times an "A C" is followed by a "B D,"
and how many (these could be 2 columns of data or one). So, output for
the above would be:

1: 1
2: 1

I think the way to do it would be to sum over a frequency, but I can't
figure out how to set the bin array the way I need it. The bins would
have to start at "A C" and reset after any "A <C"

Thoughts? Maybe a way to do it that way or a better way entirely?

Thanks for your help,