"splitEachLabel" built-in function does not really randomize the picture distribution?
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When I use R2017b to do deep learning classification, the imageDatasotre object is divided into training and test set,whether or not to specify the number or proportion, 'splitEachLabel' optional parameters specified as 'randomized', the training set inside the picture is not randomly arranged, and why?
as the document said: https://cn.mathworks.com/help/nnet/examples/create-simple-deep-learning-network-for-classification.html
digitDatasetPath = fullfile(matlabroot,'toolbox','nnet','nndemos', ...
'nndatasets','DigitDataset');
digitData = imageDatastore(digitDatasetPath, ...
'IncludeSubfolders',true,'LabelSource','foldernames');
trainingNumFiles = 750;
rng(1) % For reproducibility
[trainDigitData,testDigitData] = splitEachLabel(digitData, ...
trainingNumFiles,'randomize');
When you open "trainDigitData.Files" and "trainDigitData.Labels" in a workspace, they do not disrupt the order?
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채택된 답변
Wentao Du
2018년 3월 1일
Here the order you see will not be completely different because the labels of "digitData" are in order (from 0 to 9). To observe the effect of "randomize" parameter, you can run
[trainDigitData,valDigitData] = splitEachLabel(digitData,trainNumFiles,'randomize');
multiple times and will find the distribution of actual image files keeps changing.
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추가 답변 (1개)
cui,xingxing
2018년 3월 1일
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debojit sharma
2023년 7월 8일
Since,it may be risky to do a standard random train/test split when having strong class imbalance.Because very small number of positive cases, we might end up with a train and test set that have very different class distributions. We may even end up with close to zero positive cases in our test set. So, is there anyfunction to do stratified sampling during train/test split that avoids disturbing class balance in our samples in MatLab @cui @Wentao Du . Like the following code in python:
from sklearn.model_selection import train_test_split
train, test = train_test_split(data, test_size = 0.3, stratify=data.buy)
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