How to search for a condition in all index in a row

1 次查看（过去 30 天）
Helena Hjørringgaard
回答： Parag Jhunjhunwala 2023-6-12
Hello,
I have quite a big matrix where I need it to find the next number in a row smaller than 45.20
e.g.
0.7 45.03 45.15 44 44
0.4 45.20 44 44 44
0.5 45.20 44.3 44 44
0.38 45.20 44.9 44 44
The bold marking i is our point of interest:
What I need is: 0,7 is added to 45,03, and if ans i larger than 45,20, the surplus is added to 45,15. If this again results in a surplus, this is added to 44 (i-1,j+1) and so forth.
The correct answer should be:
0.7 45.03 45.15 44 44
0.4 45.20 45.20 44.48 44
0.5 45.20 44.20 44.88 44
0.38 45.20 45.2 45.2 44.18
Since I have a large matrix I cannot just use (which is my currently code)
if A(i,j-1) == 45.20 && A(i-1,1) + A(i-1,j-1) > 45.20
A(i,j) = A(i-1,1) + A(i-1,j-1) - 45.20 + A(i-1,j);
if A(i,j) > 45.20
A(i,j+1) = A(i,j+1) - 45.20 + A(i-1,j+1);
A(i,j) = 45.20;
end
end
because it gets the wrong answer in colums later on. I therefore need it to search for the next value smaller than 45.20 and then fill it up.
  1 个评论
KSSV
KSSV 2020-12-7
Read about logical indexing. You need not to use a loop. At a stretch you can get all the indices which are less than 45.20
idx = A(:,2)<=45.20 ;

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Parag Jhunjhunwala
Parag Jhunjhunwala 2023-6-12
Hi @Helena Hjørringgaard,
Below is the sample code to address the problem you are facing.The approach to the implementation is covered in comments in the code.
% Traverse the rows of the matrix from top to bottom excluding the last row
for i=1:n-1
% Initialize the remainder value as the value at first column of the ith row
rem=A(i,1);
% Traverse the columns of the ith row starting from the 2nd column
for j=2:m
% If the remainder becomes 0 move on to the next row iteration
if(~rem)
break;
end
% if the sum of remainder and the value at ith row and jth column is greater than 45.2(stored as
% val),assign val to the element just below it and update the remainder otherwise assign the sum
% to the element just below it and move on to the next row iteration(by making remainder 0)
if(rem+A(i,j) >= val)
A(i+1,j)=val;
rem=rem+A(i,j)-val;
else
A(i+1,j)=rem+A(i,j);
rem=0;
end
end
end

类别

在 Help Center 和 File Exchange 中查找有关 Matrix Indexing 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by