How to compare and combine two matrix

Hello

I'm new into matlab and could'nt find help to my problem.

I have two large dataset that I want to combine so that each line corresponds to right value. In my dataset every line has a unique id (matrix column 1) and i want to find the lines with same id in a two different dataset and combine them into one.

So:

How can I do a loop that compares a value in two different matrix and then writes the result as a new. The value that is compared is written only once in outcome.

Lets say I have matrix A1 and A2 and I want a loop that compares if the values in first row are the same in A1 and A2. If this happen it combines the lines to a new variable. So in this case I would compare the first value in first column --> in line 2 and line 4 the first number match--> Result is the lines added without the first column in variable 2.

A1 =

3 3 5 3

8 1 5 2

6 4 5 6

7 4 7 1

A2 =

6 3 5

8 4 3

9 7 9

7 5 1

Outcome A3=

8 1 5 2 4 3

7 4 7 1 5 1

I have a code already that compares the value but how to generate the matrix A3 in a loop.

[m,n] = size(A1);
for i = 1:n
    if isequal (A1(1,i),A2(1,i));
    B(i,:)=[A1(i,:),A2(i,:)];
    end
end
B

Cheers

Answer 1

[madhan ravi]

idx=A1(:,1)==A2(:,1);
A3=[A1(idx,:),A2(idx,2:end)]

[madhan ravi]

2016a <= versions

idx=bsxfun(@eq,A1(:,1),A2(:,1));
A3=[A1(idx,:),A2(idx,2:end)]

[Ville Koivunen]

Well that was easy, thanks. Apparently thi sworks also if I have more than two matrix to compare

[Ville Koivunen]

Hello

Apparently this doesent work when the sizes are not equal. My first matrix has hundreds of rows and other one just few. Should i resize the matrix or is there another way.

[madhan ravi]

Simply illustrate with an example and explicitly state your desired result with 2 by 3 and 3 by 3 matrix or whatever.

[Ville Koivunen]

A2=[1 2 3; 4 5 6; 7 8 9];
A1=[4 3; 1 2];
idx=A1(:,1)==A2(:,1);
A3=[A1(idx,:),A2(idx,2:end)];

this script gives an error

Matrix dimensions must agree.

Error in Untitled6 (line 30)

idx=A1(:,1)==A2(:,1);

As the number four is the common variable in column 1. Desired outcome would be in this case.

A3=

4 3 5 6

[madhan ravi]

Why did you exclude one? Explain the logic behind it.

[Ville Koivunen]

Well in my real data is in 75890x9 and 40x6 matrixes and I just wanted to sho example. Rows have a common factor on line 1 and I want to combine them. So I could handle the measured data in one piece and not to manually find the coresponding rows. Row 1 just indicates the measurement point.

Maybe I have been wrong and it would be better to handle data as tables. But still I need to do the same thing.

Example (little part) from real data

A1=[...
    184363	1119	0	3
    184370	1766	3	25];

A2=[...
    184363	404	0.36	0.58	0.71	0.60	0.463
    184364	128	0.47	0.63	0.76	0.63	0.57
    184365	43	0.61	0.74	0.831	0.76	0.65
    184370	13	0.55	0.61	0.70	0.60	0.565];

outcome desired

A3=[...
    184363	1119	0	3       404	    0.36	0.58	0.71	0.60	0.463
    184370	1766	3	25      13	    0.55	0.61	0.70	0.60	0.565];

[madhan ravi]

[ ii, lo ] = ismember( A1(:,1), A2(:,1) );
A3 = [ A1, A2( lo(ii), 2:end ) ]

[Ville Koivunen]

Oh yes, now it works Thank you sir