If I want to make a code more generalize and reduce for loop what should I do? here is my code. Here in the very beginning I have written a code only to make 3X3 matrix instead of that if I want to make nXn matrix what should I do?

Question

Mouli Sarkar 2021-4-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/800916-if-i-want-to-make-a-code-more-generalize-and-reduce-for-loop-what-should-i-do-here-is-my-code-here

回答： Zinea 2024-2-23

clc

clear

A=csvread('topo.txt');

for iter=1:size(A,1)

vec(:,:,iter)=[A(iter,2:4);A(iter,5:7);A(iter,8:10)];

end

% loop over each row

for k=1:size(A,1);

vec_=vec(:,:,k);

% vec_=[0 0 0;1 0 0;0 1 0];

temp=[0 0 0];

co=1;

for ii=1:size(vec_,1)

for jj=1:size(vec_,2)

if vec_(ii,jj)~=0

value=vec_(ii,jj);

if vec_(ii,jj)==-1 % condition: if value is -1 use 2 instead

value=2;

end

temp(co,:)=[jj,ii,value];

co=co+1;

end

% the above loop analyze the matrix

% the following loop renames the column and row indices

% using char(65)='A', char(66)='B'... and save file in the current

% directory

newfile=strcat(sprintf('%d',A(k,1,1)),'.txt');

fileID = fopen(newfile,'w');

fprintf(fileID,'%s %s %s\n','Source','Target','Type');

for ii=1:size(temp,1)

a=num2str(temp(ii,1)+64,'%s');

b=num2str(temp(ii,2)+64,'%s');

fprintf(fileID,'%s %s %d', a, b, temp(ii,3));

fprintf(fileID,'\n');

end

fclose(fileID);

% the following piece creates a separate directory and move the file

newdir = sprintf('%d',A(k,1,1));

mkdir(newdir)

movefile(newfile,newdir)

end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Zinea 2024-2-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/800916-if-i-want-to-make-a-code-more-generalize-and-reduce-for-loop-what-should-i-do-here-is-my-code-here#answer_1415038

在 MATLAB Online 中打开

Hi Mouli Sarkar,

Attached below is the code with the following changes:

Matrix dimension is nxn and not hardcoded.
Nested for-loops are removed by using vectorized operations. This increases readability as well as performance of code. You can read about vectorized operations here Vectorization - MATLAB & Simulink - MathWorks India

n = sqrt(size(A, 2) - 1); % Assume A has 1 column for ID and n^2 columns for matrix values 
for iter = 1:size(A,1) 
    vec(:,:,iter) = reshape(A(iter,2:end), [n, n]); 
end 
% loop over each row 
for k = 1:size(A,1) 
    vec_ = vec(:,:,k); 
    temp = []; 
    [row, col, val] = find(vec_); % Use find to get the non-zero values and their indices 
    
    % Replace -1 with 2 
    val(val == -1) = 2; 
    temp = [col, row, val]; % Concatenate the columns and values 
    % Add your code for write to file and create a separate directory  
end 