How to deal with Index exceeds the number of array elements ?

Question

Tomaszzz 2022-1-31

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1639710-how-to-deal-with-index-exceeds-the-number-of-array-elements

回答： Ankit 2022-1-31

采纳的回答： Ankit

signal.mat

在 MATLAB Online 中打开

Hi all,

I have a signal like this (also attached).

I want to extract signal between first start and first end, second start and second end and so on. I am doing this like this:

 load 'signal'       
    start_location = [147,222,302,379,458,538,620,698,777];
    start_value = [-81.905,-87.408,-86.262,-85.463,-85.893,-84.910,-84.614,-83.543,-84.500]    
    end_location = [200,275,352,431,511,593,674,762];
    end_value = [-85.369,-85.028,-82.240,-80.933,-80.943,-80.082,-83.108,-85.543];
    
    plot(thigh_orient_y,'k')
    hold on
    plot(start_location,start_value,'ro')
    plot(end_location,end_value,'g*')
    h = legend('signal','start', 'end');
    
    %Settings
    a = start_location ;
    b = end_location;
    n = length(a);  
    
    %Extract data between red and green indices and put in cells
    T_or_y_cycle = cell(n,1) ;
   
    for i = 1:n
    T_or_y_cycle{i} = thigh_orient_y(a(i):b(i)) ;
    end

I am getting error

Index exceeds the number of array elements

Beacuse there is larger number of 'start' than 'end', as the signal is cut at the end. Can you please help how to deal with this?

The n cannot be lenght(b) beacuse the signal can be cut at the begging and start with 'end' like here:

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Ankit 2022-1-31

编辑：Ankit 2022-1-31

How about choosing the size based on minimum value of n = min(length(a),length(b)) ?

Tomaszzz 2022-1-31

编辑：Tomaszzz 2022-1-31

Thanks, this does the trick, how can I accept you answer?

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Answer 1

Ankit 2022-1-31

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1639710-how-to-deal-with-index-exceeds-the-number-of-array-elements#answer_885375

在 MATLAB Online 中打开

 load 'signal'       
    start_location = [147,222,302,379,458,538,620,698,777];
    start_value = [-81.905,-87.408,-86.262,-85.463,-85.893,-84.910,-84.614,-83.543,-84.500]    
    end_location = [200,275,352,431,511,593,674,762];
    end_value = [-85.369,-85.028,-82.240,-80.933,-80.943,-80.082,-83.108,-85.543];
    
    plot(thigh_orient_y,'k')
    hold on
    plot(start_location,start_value,'ro')
    plot(end_location,end_value,'g*')
    h = legend('signal','start', 'end');
    
    %Settings
    a = start_location ;
    b = end_location;
    n = min(length(a),length(b));  % this will avoid extra start or end value.
    
    %Extract data between red and green indices and put in cells
    T_or_y_cycle = cell(n,1) ;
   
    for i = 1:n
    T_or_y_cycle{i} = thigh_orient_y(a(i):b(i)) ;
    end