# How to replace values of a large array by the values of a smaller one?

10 views (last 30 days)
Emerson De Souza on 13 Nov 2011
I have two tables T1 and T2 with identical number of columns but different number of raw.
The x,y,z columns from both tables were created as below:
clear all;
close all;
XSTART=5;
XEND=20;
YSTART=5;
YEND=15;
STEP1=1;
STEP2=5;
%******************* CREATE TABLE1 ********************
xvector1 = XSTART:STEP1:XEND;
yvector1 = YSTART:STEP1:YEND;
numX1 = numel(xvector1);
numY1 = numel(yvector1);
yvector1 = repmat(yvector1(:),numX1,1);
xvector1 = repmat(xvector1 ,numY1,1);
COORDINATES1= [xvector1(:) yvector1];
VALUE1=(1:1:numX1*numY1)';
VALUE1(1:end,1)=10;
T1=[COORDINATES1 VALUE1];
%******************* CREATE TABLE2 ********************
xvector2 = XSTART:STEP2:XEND;
yvector2 = YSTART:STEP2:YEND;
numX2 = numel(xvector2);
numY2 = numel(yvector2);
yvector2 = repmat(yvector2(:),numX2,1);
xvector2 = repmat(xvector2 ,numY2,1);
COORDINATES2= [xvector2(:) yvector2];
VALUE2 =(1:numX2*numY2)';
T2=[COORDINATES2 VALUE2];
Now I want to create a table T3 replacing the values of the third column from T1 by the values of the third column from T2 with the same x,y- coordinate.
The expected T3 after proper substitution will have the following components:
5 5 1
5 6 10
5 7 10
5 8 10
5 9 10
5 10 2
5 11 10
5 12 10
5 13 10
5 14 10
5 15 3
6 5 10
6 6 10
6 7 10
6 8 10
6 9 10
6 10 10
6 11 10
6 12 10
6 13 10
6 14 10
6 15 10
7 5 10
7 6 10
7 7 10
7 8 10
7 9 10
7 10 10
7 11 10
7 12 10
7 13 10
7 14 10
7 15 10
8 5 10
8 6 10
8 7 10
8 8 10
8 9 10
8 10 10
8 11 10
8 12 10
8 13 10
8 14 10
8 15 10
9 5 10
9 6 10
9 7 10
9 8 10
9 9 10
9 10 10
9 11 10
9 12 10
9 13 10
9 14 10
9 15 10
10 5 4
10 6 10
10 7 10
10 8 10
10 9 10
10 10 5
10 11 10
10 12 10
10 13 10
10 14 10
10 15 6
and so on.
I hope someone knows how to do it.
Emerson

Daniel Shub on 13 Nov 2011
Is this what you mean:
T3 = T1;
[c, ia, ib] = intersect(T2(:, 1:2), T3(:, 1:2), 'rows');
T3(ib, 3) = T2(ia, 3)
Emerson De Souza on 13 Nov 2011
yes, your suggestion does exactly what I mean.
Is there a way to reformulate these lines and express them depending on the STEP1 and STEP2 as parameter?

### Community Treasure Hunt

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

Start Hunting!

Translated by