How to find the same multiple elements in two different matrices

Hi! Personally I am new comer for using MATLAB.

So please pardon me if my question seems easy to you.

I have two matrices

Matrix A = X Y Z S; %XYZ is the coordinate and S is the slope values

Matrix B = X Y Z D %XYZ is also the coordinate and D is the displacement values

This aims to find the same XYZ between matrix A and matrix B so that I can overlay the slope and displacement values within the same XYZ.

said matrix_A =

684985 3640891.9998 606.3228 20.95918

684985 3640890.9998 606.3158 24.53832

684985 3640889.9998 606.2890 21.29358

684985 3640888.9998 606.2283 17.91158

684985 3640887.9998 606.0254 18.56814

684985 3640886.9998 605.7449 21.54986

684985 3640885.9998 605.5593 26.87469

684985 3640884.9998 605.5601 29.04047

684985 3640883.9998 605.5554 28.95754

684985 3640882.9998 605.0802 40.39104

684985 3640881.9998 603.6958 49.32053

684985 3640880.9998 603.6613 50.2536

684985 3640879.9998 605.6673 45.09067

684985 3640878.9998 606.2387 32.24639

684985 3640877.9998 606.1561 38.44921

684985 3640876.9998 605.9392 41.90742

684985 3640875.9998 605.6975 42.67643

684985 3640874.9998 605.4557 42.75308

684985 3640873.9998 605.2139 42.64434

684985 3640872.9998 604.9722 42.50702

and matrix_B =

685455 3640402.1594 569.144 -0.0287443747909282

685448 3640392.7359 570.522 -0.0287443747909282

685448 3640393.0711 570.988 -0.0287443747909282

685452 3640399.7078 569.736 -0.0287443747909282

685438 3640411.0395 579.175 -0.0287443747909282

684985 3640886.9998 605.7449 0.00655349653231637

684985 3640885.9998 605.5593 0.00655349653231637

684985 3640884.9998 605.5601 0.00655349653231637

684985 3640883.9998 605.5554 0.00655349653231637

684985 3640882.9998 605.0802 0.00655349653231637

684985 3640881.9998 603.6958 0.00655349653231637

684985 3640880.9998 603.6613 0.00655349653231637

684985 3640879.9998 605.6673 0.00655349653231637

684985 3640878.9998 606.2387 0.00655349653231637

684985 3640877.9998 606.1561 0.00655349653231637

I have huge matrix size, not only this simple example. Also, matrix A is larger than matrix B, since it represents the whole area, while matrix B is just a part of it. I am sorry if my explanation is a bit messy.

I have tried to use:

inputA = matrix_A(:,1:3);

inputB = matrix_B(:,1:3);

[iC,ia,ib] = intersect(inputA, inputB);

dummyan = [dummyclean(ia,1:4) Disp(ib,4)];

but it got me an error.

Hopefully someone can understand and help me.

Thank in advance!

Answer 1

[KSSV]

REad about ismember. Let A and B be your matrices.

[idx,ia] = ismember(A(:,1:3),B(:,1:3),'rows') ;

A(idx,:)
B(idx,:)

[DV]

Hi! Thank you for the answer.

I tried this too, but I want to get an exactly the same of XYZ between two matrices. Sorry for my unclear explanation.

[KSSV]

Off course you will get exactly same XYZ between two matrices.

Answer 2

[Stephen23]

Do NOT use ismember! Because of the floating-point numbers you should use ismembertol:

>> [idx,idy] = ismembertol(B(:,1:3),A(:,1:3),'ByRows',true)
>> C = [A(idx,:),B(idy(idx),4)]
C =
   6.8498e+05   3.6409e+06   6.0574e+02   2.1550e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0556e+02   2.6875e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0556e+02   2.9040e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0556e+02   2.8958e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0508e+02   4.0391e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0370e+02   4.9321e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0366e+02   5.0254e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0567e+02   4.5091e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0624e+02   3.2246e+01   6.5535e-03
   6.8498e+05   3.6409e+06   6.0616e+02   3.8449e+01   6.5535e-03