randomly select elements of an array

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Noe alvarado
Noe alvarado 2012-4-12
评论： Steven Lord 2022-2-7
Hi How i can select randomly elements from a matrix o array
I have the matrix and i want to select "x" numbers of elements
thanks

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Walter Roberson
Walter Roberson 2012-4-12
msize = numel(YourMatrix);
idx = randperm(msize);
YourMatrix(idx(1:x))
If you have a fairly new version of MATLAB, you can instead use
msize = numel(YourMatrix);
YourMatrix(randperm(msize, x))
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Jaime Gurrola
Jaime Gurrola 2020-12-7
Hi walter, i want to select a random element from this array, help please
A={'Yellow','Green','Blue','Orange','Black','Grey','Red','Brown','Purple','White'};

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Prasobhkumar P. P.
Prasobhkumar P. P. 2020-7-28
编辑：Walter Roberson 2021-9-3
histHandle= histfit(data,nBins,'normal');
[Val Ind] = max(histHandle(2).YData); %histHandle(2) corresponds to the curve fitted
M = histo18(2).XData(Ind);
Adam Wyatt
Adam Wyatt 2021-9-3
编辑：Adam Wyatt 2021-9-3
Ran in:
Use "randsample"
For array:
Arry = [1 4 5 7 8 9];
Smpl = randsample(Arry, 3)
Smpl = 1×3
9 5 4
For strings:
Arry = ["Yellow" "Green" "Blue" "Orange" "Black" "Grey" "Red" "Brown" "Purple" "White"];
Smpl = randsample(Arry, 2)
Smpl = 1×2 string array
"Purple" "Brown"
How do you want to sample the matrix? If its any element, just convert to array (e.g. Mat(:)). Otherwise you have to apply the function to each row/column separately.
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Piyush Kant
Piyush Kant 2022-2-7
Is there any method/parameter with which we can reproduce same random series so that the different algorithms can be evaluated? I know that way it wont be a random series anymore still the psudorandomness can be helpful for multiple runs.
Steven Lord
Steven Lord 2022-2-7
See the "Control Random Number Generation" topic on this documentation page.
Some older functions that use random numbers internally (like eigs, which generates a starting point at random if one is not given to it) have the ability to specify inputs that avoid the randomness (in the case of eigs by specifying v0 in the options structure or specifying the StartVector name-value pair argument.)

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