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

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!

Answer 1

[Dave Behera]

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.