working with an array

I have a program that cuts out points from a two-dimensional vector that are at a distance 'd' from each other. The program starts working from the first element of the second column of the array. I want to add the value 'x0' to the value of this element and that the program starts with this value.

I have attached the vector to the message.

Thank you in advance.

This is my code:

format longG
d = 0.4053/sqrt(3); %0.4053
ii = 2;
a_0 = 0;
%a_0 = optimvar('a_0',43521); %!!!!!!!!!!!!!!!
general_t_d(:,1) = gn_nach(:,1);

Unrecognized function or variable 'gn_nach'.

general_t_d(:,2) = gn_nach(:,2);
general_t_d(:,2) = general_t_d(:,2) + a_0; % addition a_0
while ii < size(general_t_d,1)
    if abs(general_t_d(ii+1,2) - general_t_d(ii,2)) < d
        general_t_d(ii+1,:) = [];
    else
        ii = ii + 1;
    end
end

[Image Analyst]

Where is the rest of the code, like the code that instatiates gn_nach and x0??? Did you try to use x0 in your code anywhere yet? Can you give a small example with the inputs and expected output?

By the way, vectors in MATLAB are 1-D. If it's 2-D it's a "matrix" or "array", and if it's higher than 2-D it's an "array".

[Dmitry]

I will try to explain with an example:

we start from B1, if mod(B1 - B2) < 0.22 we delete A2B2 and continue to compare B1 with B(i), if B1 - B(i) >= 0.22 we leave this element (A(i)B(i)) fixed on it and similarly move down the table.

I attached the table to the comment.

this is how my code works now. I want this 'cutting' to work not from the beginning B(1) but from an element whose value is B(1)+0.00015, and all previous elements A(i)B(i) to be deleted. And that's all. Thank you in advance!

[Dmitry]

Image Analyst, sir

Answer 1

[Vedant Shah]

Hi @Dmitry,

The provided MATLAB code operates on a two-dimensional array, where the second column contains values that are iteratively compared to filter out rows based on a specified distance threshold, d.

To modify the behaviour such that the filtering process begins from a value offset by a small amount ‘x0’ from the first element in the second column, it is necessary to first define ‘x0’. Subsequently, all rows with second-column values less than this adjusted starting point should be removed prior to initiating the filtering logic.

Below is the revised version of the code that incorporates this functionality:

format longG 
d = 0.4053/sqrt(3); 
x0 = 0.00015; 
a_0 = 0; 

general_t_d = gn_nach; 
general_t_d(:,2) = general_t_d(:,2) + a_0; 

% Remove rows where B < B(1) + x0 
start_value = general_t_d(1,2) + x0; 
general_t_d = general_t_d(general_t_d(:,2) >= start_value, :); 

ii = 1; 
while ii < size(general_t_d,1) 
    if abs(general_t_d(ii+1,2) - general_t_d(ii,2)) < d 
        general_t_d(ii+1,:) = []; 
    else 
        ii = ii + 1; 
    end 
end 

This approach ensures that the filtering begins from the desired offset and that all preceding data points are excluded from the analysis.

For more information, refer to the following documentations:

• https://www.mathworks.com/help/releases/R2022b/matlab/relational-operators.html
• https://www.mathworks.com/help/releases/R2022b/matlab/math/array-indexing.html