randomly divide a matrix

Question

baran 2017-5-21

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https://ww2.mathworks.cn/matlabcentral/answers/341218-randomly-divide-a-matrix

评论： Star Strider 2021-6-6

hi, i have a 16435*25 matrix that name is input, i want to randomly divided it in 2 parts: one for train and another for validate data, that 70% of its rows randomly selected as train matrix (i.e 11504*25 matrix) and 30% of its rows randomly selected as validate matrix (i.e 4930*25), how can i do this? thanks a lot

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Answer 1

Star Strider 2017-5-21

2
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https://ww2.mathworks.cn/matlabcentral/answers/341218-randomly-divide-a-matrix#answer_267831

在 MATLAB Online 中打开

For your matrix:

row_idx = randperm(16435, 11504)';

To illustrate:

example = randperm(10, 7)'
example =
     5
     8
     2
     4
     7
     3
    10

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Star Strider 2017-5-21

在 MATLAB Online 中打开

My code will create the random row indices for you. To create your training and testing matrices, use this code with your own ‘Data’ matrix. I chose a shorter matrix for convenience.

The Code —

Data = randi(9, 10, 5)                                      % Create Data Matrix
row_idx = randperm(10, 7)'                                  % Vector Or Random Rows — Use The ‘row_idx’ I Created For Your Larger Matrix In Your Code
Train_Idx = logical(zeros(size(Data,1),1));                 % Logical Vector
Train_Idx(row_idx) = true;                                  % Training Rows
Test_Idx = ~Train_Idx;                                      % Testing Rows
Train_Data = Data(Train_Idx,:)
Test_Data = Data(Test_Idx,:)
Data =
     7     9     4     1     9
     8     1     3     8     9
     7     8     9     9     9
     3     5     5     2     9
     1     9     7     5     7
     2     8     6     7     7
     3     2     8     1     4
     8     4     3     1     1
     9     1     7     4     4
     5     4     4     2     5
row_idx =
     1
     8
     4
     5
    10
     2
     9
Train_Data =
     7     9     4     1     9
     8     1     3     8     9
     3     5     5     2     9
     1     9     7     5     7
     8     4     3     1     1
     9     1     7     4     4
     5     4     4     2     5
Test_Data =
     7     8     9     9     9
     2     8     6     7     7
     3     2     8     1     4

This shows both how it works and that it works!

Onurcan BAL 2021-6-6

Thanks for both question and this explanation!

Star Strider 2021-6-6

My pleasure!

(A Vote would be appreciated!)

.

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Answer 2

MathReallyWorks 2017-5-21

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/341218-randomly-divide-a-matrix#answer_267833

编辑：MathReallyWorks 2017-5-21

在 MATLAB Online 中打开

Hello Dear,

Use this code. I've generated a random matrix of the same order that you want. I have randomized all the rows of matrix and then I'm selecting first 11504 rows for training and rest for validation. I hope it will be helpful.

 orderedArray = rand(16435,25); % Random Data %You can use your data here
shuffledArray = orderedArray(randperm(size(orderedArray,1)),:); %Randomizing the rows of matrix
t=zeros(11504,25); % Size of Train Data
v=zeros(4930,25); % Size of Validate Data
for i=1:11504
    t(i,:) = shuffledArray(i,:);
end
j=1;
for i=11541:16435
    v(j,:) = shuffledArray(i,:);
    j=j+1;
end