MATLAB: Unique Values based on 2 Variables

unique

This is a little complicated for me to explain, but I'll try my best. Suppose I have 2 variables, var1 and var2.

var1=[1 2 4]' %Column 1

var2(:,1)=[1 1 1 2 4 4 4]' %Column 1
var2(:,2)=[8 9 2 5 5 1 1]' %Column 2

My goal: For each value in var1, I want to refer to column 1 of var2 and find the unique number in column 2. (Forgive me, but even I find it difficult in explaining this. I will illustrate my objective)

Based on the code excerpt above,

In var1, the 1st value is 1. Compare it to var2 column 1 In var2, row 1-3 contains 1 and I wish to find the unique values in column 2.

(Answer: 8,9,2 when col1's value is 1)
(Answer: 5 when col1's value is 2) 
(Answer: 5,1 when col1's value is 4)

Again, I am very sorry for this poor explanation.

Best Answer

[a,b] = ismember(var2(:,1),var1);
out = [num2cell(var1),  accumarray(b(a),var2(:,2),[],@(x){unique(x)})];

Related Solutions

MATLAB: Remove rows of a table based on values in an array

disp('Original table');
var1=[1;1;1;1;4;1];
var2=[2;2;2;2;5;2];
var3=[0;3;3;8;8;9];
table_data=table(var1,var2,var3)
n=histc(var3(:),var3);
disp('Updated table');
table_data(find(n==1),:)=[]

Result Window:

Original table
table_data =
  6×3 table
    var1    var2    var3
    __    ____    ____
    1       2       0   
    1       2       3   
    1       2       3   
    1       2       8   
    4       5       8   
    1       2       9   
    
Updated table
table_data =
  4×3 table
    var1    var2    var3
    ____    ____    ____
    1       2       3   
    1       2       3   
    1       2       8   
    4       5       8

MATLAB: Replacement of groups of neighbor numbers giving priority to a row-wise check

Use the same method as in your previous question except now use the height of the bounding box instead of the area:

m = [2,  2,  2,  2,  2,  2,  2,  2,  2,  2;
     2,  1,  2,  2,  1,  2,  2,  2,  2,  2;
     2,  2,  1,  2,  1,  2,  1,  2,  2,  2;
     2,  2,  1,  2,  2,  2,  1,  2,  2,  2;
     2,  2,  1,  2,  1,  2,  1,  1,  1,  1;
     2,  1,  1,  2,  1,  2,  2,  2,  2,  2;
     2,  1,  2,  2,  1,  2,  2,  2,  2,  2;
     2,  1,  2,  2,  2,  2,  2,  2,  2,  2;
     2,  2,  1,  2,  2,  2,  2,  2,  2,  2;
     2,  2,  2,  2,  2,  2,  2,  2,  2,  2 ]
threshold = 4;
cc = regionprops(logical(2-m), {'BoundingBox', 'PixelIdxList'});
bbox = vertcat(cc.BoundingBox);  %bbox(:, 3) is the width, bbox(:, 4) is the height
m(vertcat(cc(bbox(:, 4) >= threshold).PixelIdxList)) = 2

Best Answer

Related Solutions

MATLAB: Remove rows of a table based on values in an array

MATLAB: Replacement of groups of neighbor numbers giving priority to a row-wise check

Related Question