Re: sampling from frequency distribution / histogram without replacement

2019-01-18 Thread duncan smith
On 14/01/2019 20:11, duncan smith wrote: > Hello, > Just checking to see if anyone has attacked this problem before > for cases where the population size is unfeasibly large. i.e. The number > of categories is manageable, but the sum of the frequencies, N, > precludes simple solutions such as

Re: sampling from frequency distribution / histogram without replacement

2019-01-15 Thread duncan smith
On 15/01/2019 17:59, Ian Hobson wrote: > Hi, > > If I understand your problem you can do it in two passes through the > population. > The thing is that I start with the population histogram and I want to generate a sample histogram. The population itself is too large to deal with each population

Re: sampling from frequency distribution / histogram without replacement

2019-01-15 Thread Ian Hobson
Hi, If I understand your problem you can do it in two passes through the population. First, however, lets work through taking a sample of 2 from 7 to demonstrate the method. Take the first element with a probability of 2/7. (Note 1). If you took it, you only want 1 more, so the probability

Re: sampling from frequency distribution / histogram without replacement

2019-01-15 Thread duncan smith
On 15/01/2019 02:41, Spencer Graves wrote: > > > On 2019-01-14 18:40, duncan smith wrote: >> On 14/01/2019 22:59, Gregory Ewing wrote: >>> duncan smith wrote: Hello,    Just checking to see if anyone has attacked this problem before for cases where the population size is unfeas

Re: sampling from frequency distribution / histogram without replacement

2019-01-14 Thread Spencer Graves
On 2019-01-14 18:40, duncan smith wrote: On 14/01/2019 22:59, Gregory Ewing wrote: duncan smith wrote: Hello,   Just checking to see if anyone has attacked this problem before for cases where the population size is unfeasibly large. The fastest way I know of is to create a list of cumul

Re: sampling from frequency distribution / histogram without replacement

2019-01-14 Thread duncan smith
On 14/01/2019 22:59, Gregory Ewing wrote: > duncan smith wrote: >> Hello, >>   Just checking to see if anyone has attacked this problem before >> for cases where the population size is unfeasibly large. > > The fastest way I know of is to create a list of cumulative > frequencies, then generat

Re: sampling from frequency distribution / histogram without replacement

2019-01-14 Thread Gregory Ewing
duncan smith wrote: Hello, Just checking to see if anyone has attacked this problem before for cases where the population size is unfeasibly large. The fastest way I know of is to create a list of cumulative frequencies, then generate uniformly distributed numbers and use a binary search