How to use softmax, Loss function(negative log probability) in classification

Question

Kong 2020-4-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/514918-how-to-use-softmax-loss-function-negative-log-probability-in-classification

回答： Shishir Singhal 2020-4-7

采纳的回答： Shishir Singhal

outfile.csv

在 MATLAB Online 中打开

Hello.

I want to classify videos.

After computation of eucldean distance, I want to use softmax and Loss function(negative log probability) for classification.

Can I get some idea to make the code?

clear all
close all
data = csvread('outfile.csv');
values = data(:,1:end-1);
labels = data(:,end);
avg = splitapply(@(x) mean(x,1), values, labels+1);
mean_class1 = avg(1,:);
mean_class2 = avg(2,:);
mean_class3 = avg(3,:);
mean_class4 = avg(4,:);
mean_class5 = avg(5,:);
bend_query = values(1,:);
run_query = values(2,:);
walk_query = values(3,:);
skip_query = values(4,:);
wave_query = values(5,:);
% calculate euclidean distance
euclidean_bend = pdist2(mean_class1, bend_query, 'euclidean');
euclidean_run = pdist2(mean_class2, run_query, 'euclidean');
euclidean_walk = pdist2(mean_class3, walk_query, 'euclidean');
euclidean_skip = pdist2(mean_class4, skip_query, 'euclidean');
euclidean_wave = pdist2(mean_class5, wave_query, 'euclidean');

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Answer 1

Shishir Singhal 2020-4-7

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/514918-how-to-use-softmax-loss-function-negative-log-probability-in-classification#answer_424525

For classification,

softmax creates probability scores for each category.

since your predictions and targets follows different probability distributions. You can use cross entropy loss for that. It is kind of negative log probability function.

Refer to this documentation for the implementation: https://www.mathworks.com/help/deeplearning/ref/dlarray.crossentropy.html