How create a matrix that matches a condition in comparison with other matrix?

Question

Philippe Corner 2020-12-1

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/671943-how-create-a-matrix-that-matches-a-condition-in-comparison-with-other-matrix

评论： Adam Danz 2021-8-9

The matrix A is given by several repeated values of A(:,1) positions with different A(:,2) values like:

clc;clear all
A=[
 10
 9
 8
 7
 6
 15
 14
 13
 12
 11
 18
 17
 16
 15
 14
 12
 11
 10
 9
 8];
scatter(A(:,1),A(:,2),'filled','r')

Represented by the following red dots:

The matrix B, represents 1 [X,Y] combination for each B(:,1) as:

%%
B=[
1   8
2   14
3   11
4   12];
 
hold on
scatter(B(:,1),B(:,2),'filled','b')

How can I eliminate all the values extrictly higher than any B(:,2) for each B(:,1) and keep only same or lower values getting a C matrix like:

%%
C=[
 8
 7
 6
 14
 13
 12
 11
 12
 11
 10
 9
 8];
scatter(C(:,1),C(:,2),'filled','g')

green dots represent the wanted points to keep.

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Answer 1

Adam Danz 2020-12-2

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/671943-how-create-a-matrix-that-matches-a-condition-in-comparison-with-other-matrix#answer_562928

在 MATLAB Online 中打开

A=[
 10
 9
 8
 7
 6
 15
 14
 13
 12
 11
 18
 17
 16
 15
 14
 12
 11
 10
 9
 8];
B=[
 8
 14
 11
 12];
idx =  cell2mat(arrayfun(@(i){A(:,1)==B(i,1) & A(:,2)<= B(i,2)},1:size(B,1))); 
[rowIdx,~] = find(idx);
C = A(rowIdx,:)
C = 12×2
   8
   7
   6
  14
  13
  12
  11
  12
  11
  10
●

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Philippe Corner 2021-8-8

Hello Adam, could you check this question? I think you may help me to find the best way to solve it.. https://it.mathworks.com/matlabcentral/answers/894752-how-to-assign-values-to-a-mesh-based-on-xyzc-points