# create random-order list with items not repeating within 8 occurences

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Darya Frank on 4 Apr 2016
Answered: Dave Behera on 6 Apr 2016
I'm quite new to Matlab and any help/ideas would be much appreciated! I have a list of 240 strings in a cell that look like:
1a b
1a f
1b f
1b b
1c f
1c b
1d f
1d b
2a b
2a f
etc. until 30d...
I'm trying to re-order this list such that there's at least 8 occurrences between 1X (x=a,b,c,d) and any other 1X, with each occurring only once.
For example:
1a
5d
8c
29b
27a
12a
30b
9c
1d
Does anyone have any idea where to start? I've tried using randperm and a custom-built randswap functions but I can't seem to figure out how to make it fulfil the min-8 occurrences condition
Many thanks!

Dave Behera on 6 Apr 2016
You could use this approach:
1. Create a empty cell array A
A = {}
2. Go through the list looking for 1_x strings (using for loop). Every time one is found, create a new cell array beginning with that string. Add this new cell array to the array A. In the end, A should look like: { {1_a}, {1_b},.....}
3. Go through the list again, this time looking for non- 1_x strings. Add each such string to a different cell array in A, so that each cell array for a 1_x string gets populated. One way would be to add the 1st string to A{1}, .ie {1_a} in example above, 2nd string to {1_b}, etc. When end of A is reached, add the string to A{1} again and repeat.
In the end, A should look like:
{ {1_a, 5_d, 6_c.....}, {1_b, 7_g,......},.....}
4. Then, concatenate all the cell arrays inside A into a single cell array, which will be the final answer.