Generate 0 and 1
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Hi,
How to generate 0 and 1 with equal probability?
I wanna generate sequence like 010101 or 011001 i.e probability of 0 and 1 should be 0.5.
3 个评论
gkboy
2018-8-7
Hey,I am trying to get the random matrix with the elements only 1 and 0 where none of columns and rows can be 0 only and also the number of 0s and 1s should be in a percentage of 30% and 70%. have to use probability
Requirements 1 Random Matrix 2. elements only 1s and 0s 3. percentage of 0s: 1s is 3:7 4. None of the columns and rows can be with only 0 and only 1. have to have mix
James Tursa
2018-8-8
This is sufficiently different from the original question that I would advise you delete this comment and instead post it as a new Question.
Srik G
2022-1-27
I wanna generate sequence like 010101 or 011001 with some sampling time in matlab- simulink blocks. Please suggest the block which can do this job in simulink ?
采纳的回答
Walter Roberson
2012-5-9
round(rand)
or
rand >= 0.5
4 个评论
Ronak Sakaria
2012-5-9
Walter Roberson
2012-5-9
T = [zeros(1,N), ones(1,N)];
T = T(randperm(2*N));
Warning: if you force the number of 1 and 0 to be equal, then that is _not_ a Uniform Random Distribution. The last bit could be completely predicted by knowing all the other bits.
Katyayani Modi
2017-9-23
He i have one question I want to generate 1's or 0's but 1's will occur 70% of the time with round, ceil, fix, floor function.
Image Analyst
2017-9-23
To get a specified percentage of 1's, try this:
numberOfElements = 1000; % Whatever.
percentageOfOnes = 70; % Whatever.
numberOfOnes = round(numberOfElements * percentageOfOnes / 100)
% Make initial signal with proper number of 0's and 1's.
signal = [ones(1, numberOfOnes), zeros(1, numberOfElements - numberOfOnes)];
% Scramble them up with randperm
signal = signal(randperm(length(signal)));
% Count them just to prove it
numOnes = sum(signal)
更多回答（8 个）
Image Analyst
2012-5-9
Ronak, This will do the trick:
n = 10; % Total length must be even to have even # of 0s and 1s.
numberOfOnes = n/2
% Get a list of random locations, with no number repeating.
indexes = randperm(n)
% Start off with all zeros.
x = zeros(1, n);
% Now make half of them, in random locations, a 1.
x(indexes(1:numberOfOnes)) = 1
Geoff
2012-5-9
I wouldn't do this using the double version of rand. While it's not really incorrect to use rand for this, I would use randi instead. Integers are the native data type for random number generation.
This generates an m-by-n matrix of zeros and ones:
x = randi(2,m,n) - 1
There is still a chance, however, that when generating six random numbers they will be all 1, all 0, or anything else where the distribution is not perfect. If you require an equal number of ones and zeros, but scrambled, you could do this:
% By definition, we require an EVEN number for N
N = 6;
x = repmat([0 1], 1, N/2);
% Randomly switch two individual numbers N times.
for t = randi(N, 2, N)
x(t) = x(t([2 1]));
end
[edited: made swap code less C-like]
5 个评论
Ronak Sakaria
2012-5-9
Geoff
2012-5-9
Oh, thanks Walter for pointing out the randperm() function. Didn't know that one. Ronak, to explain my loop (since you emailed me to ask about it):
I generate a 2xN array of indices and loop over it. Each iteration of the loop gives me a column-vector 't' containing two random indices. I then swap the values of 'x' at those two indices (even if they're the same). The x(t([2 1])) gives me the same two values of x but in reverse order (since I reversed the 't' vector).
Daniel Shub
2012-5-9
I think randi uses the same random number generator as rand. As none of the random number generator give you logicals (what you want), I don't see why int8 is that much better than double.
Walter Roberson
2012-5-9
Integers are (nearly always) what underlies uniform random generators. However, other distributions such as rand() may use other methods.
MATLAB does not expose the 32 bit integer generation capability of the Twister algorithm. If I recall, it uses two Twister calls to generate the 53 bit double in rand().
I do not have access to randi() to check, but because it needs to be uniform random over a variable range of integer values (rather than always over a power of 2), fairness considerations usually make it easier to use a double and multiply by the span.
Walter Roberson
2012-5-16
I meant to write that randn() may use other methods.
Narayan Chaudhary
2012-5-16
randerr(1,6,[0 3;0 1])
1x6 matrix with 0 and three non-zero entries with probability of 3 non zero entries being 1 i.e. 0,5 in overall matrix
1 个评论
juan camilo lores acosta
2020-3-18
muchas gracias salvaste una vida :)
Haoming Mai
2018-2-24
0 个投票
Hi
How to generate 0 and 1 with probability of 1/3?
1 个评论
Image Analyst
2018-2-24
编辑：Image Analyst
2018-2-24
With randperm
total = 99
numOnes = round(total/3)
r = zeros(1, total); % All zeros to start.
% Now assign a third of them to 1
indexes = randperm(total, numOnes);
r(indexes) = 1
sum(r) % Check to make sure. Should be 33
I already showed this above in https://www.mathworks.com/matlabcentral/answers/37827-generate-0-and-1#comment_486991
Walter Roberson
2018-2-24
编辑：James Tursa
2018-8-8
0 个投票
A few years after this question was posted, I posted
In which I proved that it is not possible to generate 0 and 1 with exactly equal probability with any of the MATLAB random number generators.
Akira Agata
2020-3-18
Just FYI:
To evaluate BER (Bit Error Rate) of digital communication system, PRBS (Pseudo Random Binary Sequence) has been commonly used as a test pattern for many years. Since PRBS sequence with length of 
bits always contains specific number of 1s and 0s (more precisely, 
1s and 
0s ), maybe you can use this for your purpose.
bits always contains specific number of 1s and 0s (more precisely, 1s and 0s ), maybe you can use this for your purpose.% For example, the following code generates PRBS sequence of r=4 (15bit length)
pnSequence = comm.PNSequence(...
'Polynomial', [4 3 0],...
'InitialConditions',[0 0 0 1],...
'SamplesPerFrame', 15)
prbsSequence = pnSequence();
Prakash Reddy Pasham
2022-1-3
0 个投票
I just need the 1D array of zeros and Ones with our required probability of ones.
1 个评论
https://www.mathworks.com/matlabcentral/answers/37827-generate-0-and-1#comment_538887 shows how to achieve a specific density of ones -- for example, exactly 33 ones out of 99.
Note that this is not the same as the probability being 33/99 = 1/3 : probability is statistical. For example,
simulations = mean(rand(1000,1000) <= 1/3,1);
min(simulations), max(simulations)
histogram(simulations)
Omair Mohammad Ikram
2022-3-22
编辑：Image Analyst
2022-3-22
0 个投票
What is the code for generation of a random sequence of bits with a specified probability of p0 of the bit 0?
3 个评论
Image Analyst
2022-3-22
Try this:
p0 = 60; % Percent of zeros that we need in the final sequence.
numElements = 10000; % However many you want.
% Initialize a sequence of 1's.
sequence = ones(1, numElements);
numZeroes = round(numElements * p0 / 100);
% Get locations to randomly sprinkle the 0's into.
randomIndexes = randperm(numElements, numZeroes);
% Set those locations to 1.
sequence(randomIndexes) = 0;
% Verify
percentageOfOnes = 100 * sum(sequence) / numElements
percentageOfZeroes = 100 * sum(~sequence) / numElements
Adapt as needed.
Omair Mohammad Ikram
2022-3-22
Thanks alot
Walter Roberson
2022-3-22
Do you need probability or do you need a specific number of values in a state? If you need exactly floor(p0*samples) then use randperm like above. If you want probability then
out = rand(1,samples) > p0;
for probability p0 of a 0.
More common would be to specify the probability of a 1, in which case you would typically use <.
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