problem with using randsample
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mehdi J
el 7 de Nov. de 2018
Comentada: Steven Lord
el 6 de Oct. de 2020
Hi, I have a set that its members change in a loop and I want to select just one member of it randomly and evaluate the result. the written code is as below:
CandidateNode = randsample(UnvisitedNode,1);
it works good but sometimes its result is not acceptable. for example when UnvisitedNode=[3] running this code have different result. sometimes CandidateNode=[1], sometimes CandidateNode=[2] and sometimes CandidateNode=[3] how could I fix it? tanx in advanced
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Respuesta aceptada
Jeff Miller
el 7 de Nov. de 2018
When the first parameter of randsample is a single number k, the assumption is that you want a random sample from the integers 1:k. It looks like you will have to check numel(UnvisitedNode) and return its value when numel=1.
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Steven Lord
el 6 de Oct. de 2020
Alternately you could use randi instead of randsample for this particular use case.
% Build some sample data
numberOfNodes = randi(10); % Random number of nodes
UnvisitedNode = (1:numberOfNodes).^2
% Choose one of the UnvisitedNodes
selectedNode = UnvisitedNode(randi(numel(UnvisitedNode)))
This is a variant of the suggestion given in the description of the population input argument on the documentation page for the randsample function:
"If population is a numeric vector containing only nonnegative integer values, and population can have the length 1, then use y = population(randsample(length(population),k)) instead of y = randsample(population,k)."
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Aaron Schnydrig
el 6 de Oct. de 2020
The question is quite old, but for the ones finding it over Google (like I did):
The simplest answer would be the following:
CandidateNode = randsample(repmat(UnvisitedNode, 2, 1),1)
The repmat() function uses every value of your vector twice. Therefore, it will not change the probability of a certain element. However, it will make sure that your vector always has more than one element and is therefore used as a population.
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