Formula for an output of repeat occurrences in a given range of data?

You can attach the workbook here - no need for a link.

1. Make sure that your sample data are REPRESENTATIVE of your real data. The use of unrepresentative data is very frustrating and can lead to long delays in reaching a solution.

2. Make sure that your desired results are also shown (mock up the results manually).

3. Make sure that all confidential data is removed or replaced with dummy data first (e.g. names, addresses, E-mails, etc.).

4. Try to avoid using merged cells as they cause lots of problems.

Unfortunately the attachment icon doesn't work at the moment, so to attach an Excel file you have to do the following: just before posting, scroll down to Go Advanced and then scroll down to Manage Attachments. Now follow the instructions at the top of that screen.

Please pay particular attention to point 2 (above): without an idea of your intended outcomes, it is often very difficult to offer appropriate advice.

The attached workbook may help you, or at least get you started. I've created a matrix for you (section shown below). I use a grid like this when working out timetable option blocks from choices at school. Someone here gave me help with this some time ago - I think it was originally designed for a golf tournament. Hope it helps.

Excel 2016 (Windows) 32 bit

	B	C	D	E	F	G	H	I	J	K	L	M
2		A12477	A12478	A12528	A12532	A12539	A12541	A12542	A12546	A12547	A12550	A12561
3	A12477	1	0	0	1	0	0	0	0	1	0	0
4	A12478	0	1	1	0	0	1	0	0	0	0	0
5	A12528	0	1	30	0	3	9	0	0	0	18	2
6	A12532	1	0	0	31	0	0	1	3	28	2	0
7	A12539	0	0	3	0	3	0	0	0	0	0	0
8	A12541	0	1	9	0	0	9	0	0	0	0	0
9	A12542	0	0	0	1	0	0	1	1	0	0	0
10	A12546	0	0	0	3	0	0	1	3	0	0	0
11	A12547	1	0	0	28	0	0	0	0	28	2	0
12	A12550	0	0	18	2	0	0	0	0	2	20	2
13	A12561	0	0	2	0	0	0	0	0	0	2	2

Sheet: Single list of courses

It uses this formula:

=SUMPRODUCT((MMULT(('Conflict Matrix 2018.csv'!$A$3:$H$63=C$2)+('Conflict Matrix 2018.csv'!$A$3:$H$63=$B3),{1;1;1;1;1;1;1;1})=2)+0)

I've formatted the cells so that zeros do not show.

You're welcome! Shout if you need any further help.

I thought it was pretty amazing, too, when it was first offered to me as a solution about a year ago.

If that takes care of your original question, please select Thread Tools from the menu link above and mark this thread as SOLVED. Thanks.

It would be best to attach the workbook here. It will be easier to troubleshoot that way.

Still waiting to see the new, muddled workbook.

My formula will choke on entries like this, I am afraid:

A12572 Alternates:V13077

It isn't 'clever' enough to deal with alternatives. These will need to be separated out into their own columns.

However, here's how it works:

1. Make sure that you have a list of all possible (available) courses down the left and across the top of the clash matrix (these need to be in the same order top to bottom and left to right).
2. Make sure that the arrays in the formula in C3 are long/wide enough to cover the entire range of choices on the choices sheet (red sections below).
3. Make sure that the number of 1s in the matrix in the formula equal the number of columns in the lookup array (i.e. if there are 10 columns of choices, there must be 10 1s - green section below).
4. Once this is all checked, copy the formula across and down.

=SUMPRODUCT((MMULT(('Conflict Matrix 2018.csv'!$A$3:$H$63=C$2)+('Conflict Matrix 2018.csv'!$A$3:$H$63=$B3),{1;1;1;1;1;1;1;1})=2)+0)

This is what you will need, once you have checked that the lists across the top and down the side are correct:

=IFERROR(SUMPRODUCT((MMULT(('Requests by Student'!$A$1:$L$59=C$2)+('Requests by Student'!$A$1:$L$59=$B3),{1;1;1;1;1;1;1;1;1;1;1;1})=2)+0),"")

=2 checks where both criteria are met (i.e. the arrays generated by the formula added together make 2), which indicates one match

+0 just forces the calculation to be numbers

No, please do NOT change either!

I recommend you use the evaluate formula feature to step through the formula to see what it's doing.

All the IFERROR bit does is return a blank if the formula returns an error. It is still the same SUMPRODUCT MMULT formula!

Glad you understand it well enough now to adapt yourself.