how to vectorize these for loop?

Question

serena dsouza 2017-8-9

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/352096-how-to-vectorize-these-for-loop

编辑： Jan 2017-8-9

clc;
 clear all;
 close all;
tic;
[s,fs]=audioread('sample.wav')
fdatool
l=length(s);
figure('name','speechsignal');
subplot(3,3,1);
plot (s);
title('speech signal');
xlabel('samples---->');
ylabel('amplitudes---->');
t=(0:1:l-1)/fs;
subplot(3,3,2);
plot(t,s);
title('Speech signal on time axis');
xlabel('time(s) ---->');
ylabel('Amplitude ---->');
f_d=0.1;
f_s=floor(l*f_d);
overlap=f_s/2;
no_f=floor((l/f_s)*2-1);
M=zeros(f_s,no_f);
for j=1:no_f;%i=1:frame size;  
for i=1:f_s;%j=1:no of frames;
    M(i,j)=s(((j-1)*overlap)+i);
end;
end;

1 个评论
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José-Luis 2017-8-9

Please edit your code to make it easy to read.

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Answer 1

Walter Roberson 2017-8-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/352096-how-to-vectorize-these-for-loop#answer_277349

编辑：Walter Roberson 2017-8-9

在 MATLAB Online 中打开

First improvement:

for j=1:no_f                     %i=1:frame size;  j=1:no of frames;
  M(1:f_s, j)=s(((j-1)*overlap)+(1:f_s));
end

Second improvement:

M = s( bsxfun(@plus, (1:f_s).', ((1:no_f)-1)*overlap ) );

Third improvement: replace much of your code with a call to buffer()

2 个评论
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serena dsouza 2017-8-9

thank you

Jan 2017-8-9

编辑：Jan 2017-8-9

@serena dsouza: Further improvement: Omit the brute celaring header clc; clear all; close all;, which is cargo cult only and wastes a lot of time, when all functions must be imported from the slow hard disk afterwards. See Stephen's comment .

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