How to add 1 matrix to another matrix ?

I have 2 matrices with different size as show below and just want to concatenate both of them. I know 2nd matrix have 1st 6 columns entries that are lying in b/w 1st matrix somewhere, so now i just want to add last 2 column values to 1st matrix of there corresponding rows of 1st matrix. Can someone help me how to write syntax for this ?

[Azzi Abdelmalek]

You posted the two matrices, what about the result? Also you can post a small example that explain your problem

[Ahsan Abbas]

The result will be single matrix having entries of both matrices.

[Azzi Abdelmalek]

This is not clear. post the result to make it clear

[Ahsan Abbas]

x = [1 2 3; 4 5 6; 7 8 9; 10 11 12]; y = [4 5 6 12 15; 10 11 12 25 52]; result would be like z = [1 2 3 0 0; 4 5 6 12 15; 7 8 9 0 0; 10 11 12 25 52];

Answer 1

[Star Strider]

One approach, taking advantage of the fact that both of your matrices are sorted by the first column:

M1 = sortrows(rand(15, 4), 1);                                  % Create 1st Matrix & Sort By Column #1
M2 = [M1(1:5:end,:)  rand(3,2)];                                % Create 2nd Matrix & Add Columns #5 & #6

idx = find(ismember(M1(:,1), M2(:,1)));                         % Find Indices Of Matching Column #1 Entries

M1 = [M1 zeros(size(M1,1),2)];                                  % Add Zeros To End Of ‘M1’
M1(idx,5:6) = M2(:,5:6);                                        % Fill Columns #5 & #6 With Same Values From ‘M2’

Since you are dealing with floating-point numbers, if you have R2015a or later, you would likely best use ismembertol instead of ismember to guarantee that your data match.

[Ahsan Abbas]

Thanks Star Strider for helping, i am using matlab 2013b so ismember is the only option.

[Star Strider]

My pleasure.

I’m hoping that your matrix entries are exact, so that ismember will work. If not, we will work on a way to use a tolerance with it. Rounding the first column of each matrix to a particular number of decimal places first would likely be easiest.

Answer 2

[Azzi Abdelmalek]

[n1,m1]=size(x)
[n2,m2]=size(y)
z=zeros(n1,m2)
idx=ismember(x,y(:,1:m1),'rows')
z(idx,:)=y
z(~idx,1:m1)=x(~idx,:)

[Ahsan Abbas]

Thank you Azzi for your response.