comparison and replacement of values between 2 matrixes.

I have 2 Matrixes of n*4 size, where the first 3 columns are co-ordinate values and the 4th being a value for the co-ordinate.

the matrixes dont occupy the same space (co-ordinate wise) and i am wanting to find and replace the values in the 4th column of the first matrix, with the values in the 4th column of the 2nd matrix that have corresponding co-ordinate values (columns 1-3).

I am currently doing this through a series of for and if loops checking the co-ordiantes of each row of the 2nd matrix against the 1st and replacing the value of the first when they match, but given the size of the matrixes (n~1000000), this takes a long time.

Is there any way i could code this process differently to speed it up?

Answer 1

[KALYAN ACHARJYA]

"i am wanting to find and replace the values in the 4th column of the first matrix, with the values in the 4th column of the 2nd matrix that have corresponding co-ordinate values (columns 1-3)"

n=5; % Any Value, row number
%Before Exchange 4th cloumn 
% Any Radom mat
mat1=randi(20,[n,4])
mat2=randi(20,[n,4])
temp_data=mat1(:,4);
mat1(:,4)=mat2(:,4);
mat2(:,4)=temp_data;
%After Exchange 4th cloumn 
mat1
mat2