Using MNIST in MATLAB

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Jacob Ebilane
Jacob Ebilane 2022-3-11
评论： Jacob Ebilane 2022-3-13
Hello
I am new to OCRs and am trying to use the MNIST dataset in matlab. I found a csv version of the data set which is usable in MATLAB then stored it as a .mat file (Somehow loads faster, I'm not so sure why if you do know do tell me). I wanted to try it on the fitcknn command as such
clc, clear
close all;
load 'mnist_train.mat'
knnmodel = fitcknn(mnist_train,"Var1")
I tried the Onramp course and tried to mimic how they did it but I get these error messages. I wanted to know if I can make this work and how.
Error using classreg.learning.FullClassificationRegressionModel.prepareDataCR (line 234)
X and Y do not have the same number of observations.
Error in classreg.learning.classif.FullClassificationModel.prepareData (line 821)
classreg.learning.FullClassificationRegressionModel.prepareDataCR(...
Error in ClassificationKNN.prepareData (line 926)
prepareData@classreg.learning.classif.FullClassificationModel(X,Y,varargin{:},'OrdinalIsCategorical',true);
Error in classreg.learning.FitTemplate/fit (line 233)
this.PrepareData(X,Y,this.BaseFitObjectArgs{:});
Error in ClassificationKNN.fit (line 911)
this = fit(temp,X,Y);
Error in fitcknn (line 264)
this = ClassificationKNN.fit(X,Y,RemainingArgs{:});
Error in OCR (line 6)
knnmodel = fitcknn(mnist_train,"Var1");

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larasupernovae
larasupernovae 2022-3-11
So here is book, check out Chapter 6 if you are begining the MNIST in MatLab this is the best way to understand it all, hope this helps :) I also included my code from the book, a while a back when I was starting out with MNIST.
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larasupernovae
larasupernovae 2022-3-11
You probably won't do much by manual addition. The thing is the MNIST data set has an accuracy of 99%, you should be having just small anomalies when it comes down to it, using backpropagation a bit more efficiently might help (using it as a library just like in Python). The version I sent you is using the BP you make on your own, you can also use this type of code: see attachment https://we.tl/t-qA7w4fS5cO it's via we transfer since MatLab has a policy about uploading too much code :)
Jacob Ebilane
Jacob Ebilane 2022-3-13
I guess it has something to do with the algorithm I have for separating each digit. I think it has something to do with the data reaching the top of the image itself.

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