How do I sample randomly based on some probability(wightage)?

[Antoon Pardon]

Op 2009-05-26, Arnaud Delobelle schreef <arnodel at googlemail.com>:
> Sumitava Mukherjee <smukh at cognobytes.com> writes:
>
>> On May 26, 11:39 pm, Sumitava Mukherjee <sm... at cognobytes.com> wrote:
>>> Hi all,
>>> I need to randomly sample from a list where all choices have weights
>>> attached to them. The probability of them being choosen is dependent
>>> on the weights.
>>> If say Sample list of choices are [A,B,C,D,E] and weights of the same
>>> are [0.895,0.567,0.765,0.890,0.60] when I draw (say 2) samples then I
>>> want the likeliness of them being chosen be in the order : D>A>C>E>B
>
> You mean A > D > C > E > B
>
>>> In short I mean if prob of a H is .9 and probability of T be 0.1 then
>>> if I draw 10 samples, 9 should be H and 1 should be T.
>>>
>>> I coudn't find a function in the module random that does so.
>>> Please can someone guide me how the above could be implemented [either
>>> through some function which exists and I don't know or pointers to
>>> some code snippets which does so]?
>>
>>>>>> [Oh, I forgot to mention. I am looking for sampling without replacement.]
>
> If you do sampling without replacement, you need to know the exact
> number of each of A, B, C, D, E in the sample, not just their relative
> frequency.

As far as I understand, you are given the exact number of each. It is one.
The numbers given are not relative frequencies of appearance but weights
to be attributed for picking them.

-- 
Antoon Pardon