How to similuate a coin flip with probablility p

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Zach
Zach 2011-11-9
评论： ali fadi 2022-4-11
How do I simulate getting a result, either 0 or 1, with probability p. So if p=0.5 I should get an output of 0 half of the time, and 1 half of the time.

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Wayne King
Wayne King 2011-11-9
100 tosses with p=0.5.
x = round(rand(100,1));
If you want a probability other than p=0.5, then realize that rand() is uniform random number generator between [0,1], so you can assign the output of rand() accordingly. For example, for p=0.25:
y = zeros(100,1);
x = rand(100,1);
y(x<0.25) = 1;
Or if you just want to simulate the number of 0's or 1's in a certain number of trials. Say 100 for example. Here is a simulation of ten such experiments. Requires Statistics Toolbox.
R = binornd(100,0.5,10,1);

更多回答（3 个）

Nick
Nick 2011-11-9
Alternatively you could use the randi function in MATLAB which generates random integers.
100 tosses with 0=heads, 1=tails
coin=randi([0:1], [100,1])
It should more or less give you 50 0's and 50 1's.
If there is more than 2 possible outcomes and they all occur with the same probability then just increase the integer range of the randi function.
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Image Analyst
Image Analyst 2021-11-13
编辑：Image Analyst 2021-11-13
@Evangelia Lo, if you have the Image Processing Toolbox you can use bwareafilt() to extract runs of only the length you want and then bwlabel() or regionprops() to count them. If you want to find the index where each run starts, use regionprops():
coins = logical(randi([0, 1], 1, 30000)); % 30,000 coins
patternLength = 10; % Whatever you want
% Throw out all regions that don't match the length we want using bwareafilt(). Need to invert.
coins2 = bwareafilt(~coins, [patternLength, patternLength]);
% Count them
props = regionprops(coins2, 'PixelIdxList');
numPatternOccurrences = numel(props)
% For fun, find out where they occur.
indexes = vertcat(props.PixelIdxList); % All 10 indexes in a run
startingIndex = indexes(1 : patternLength : end) % Just the starting index.
Evangelia Lo
Evangelia Lo 2021-11-13
How can i do it without the Image Processing Toolbox ?

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Cory London
Cory London 2018-11-15
This code is easily minupulated and works pretty well
Ntoss = 100;
x = rand(1, Ntoss); % what is the resulting size of x?
toss = (x < 0.5);
SARATHRAJ V
SARATHRAJ V 2021-2-20
Ntoss = 100; x = rand(1, Ntoss); % what is the resulting size of x? toss = (x < 0.5);

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