Hi everybody,
Maybe a stupid question, but I forgot how to calculate such things. Let's say I have a group of 200 elements (genes). I want to divide this group into n subgroups, each containing 10 elements. However, each element should be present in more than one subgroup. Is there a cool formula to calculate n depending on the number of times each element should be present in independet subgroups?
Thanks,
Johannes
I think you meant set not group! cuz groups are sets with binary operation with 4 axioms (asscoiativity, identity, inverse, and closed operation)
Now, If you have 200 elements and you wanna compute how many subsets with 10 elements you can make, follow this formula
n=200×199×198×....×191÷(10×9×8×...×2)
Hi Mohammad
I do not really want to calculate how many possible subsets I can make. I want to make subsets with the size of 10. And each element should be present in
a) 2 subsets or
b) 3 subsets
But no more. I am wondering about the absolute number of subsets that will be required in each scenario (a, b). Each subset will represent a significant amount of lab work - so I want to keep the number of subsets small, but still include each element = gene in at least two subsets.
Thx,
Johannes
Hi Johannes,
you might give a unique number to all 200 genes (e.g. 1-200) or two unique numbers for each gene (1-400) and then "playing lotterie without replacing the numbers". In r you could use the "sample" function.
genes
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