MATLAB: Target just the last added entries to a matrix

array calculationsmatricesmatrix manipulation

Hey, I am working with matrices and I wanted to know if there is a standard way/code to target just the last added entries to a matrix. I used the general syntax for appending data points to a matrix (A= [A;B]) and I wanted to know if there was an analogous general method for targetting the last added entries into a matrix. For example, I append 4 sets of coordinates to a matrix and now I want to call just those 4 sets from the matrix and use them for next step in my code. Any help is greatly appreciated.

Best Answer

As commented:

A(end-n:end, :)

will give you the last n+1 rows of the (2D) matrix.

does your solution only work with a loop

Why do you think that? There's no loop involved in that line. It's basic matrix indexing using the end keyword.

Related Solutions

MATLAB: Sorting points based on comparing distances.

Use the 2nd output to min() to pair the points in B to the nearest points in A. Then use splitapply to segment the points in B into nearest neighbors in A. This works for any amount of coordinates in A.

% Creat demo data
A= [0	0;
    -5.52181708330649 5.78874218621840];
B = [38.8197976955836	-29.0434116907097
    -37.0532684880158	0.644925865563445
    -4.49735986053992	57.3402937422674
    -43.7442096431328	38.5935144262550
    41.5359946082739	41.4696332098067
    57.3572679057450	8.87552592324304
    -29.8320366435934	-43.1286701525403];
% compute distances between A, B
C = pdist2(A,B);
% or better: C = sqrt((B(:,1)-A(:,1)').^2 + (B(:,2)-A(:,2)').^2)';
% Split B into groups that are nearest to points in A
[~, minRowIdx] = min(C,[],1); %
neighborGroups = splitapply(@(x){x},B,minRowIdx(:));

neighborGroups{n} are all the coordinates in B that are closest to A(n,:).

MATLAB: How to display string of matrix in one edit text

a={'somename';'diffname';'something'};
set(handles.EditBox, 'Max', 2, 'String', a);

Best Answer

Related Solutions

MATLAB: Sorting points based on comparing distances.

MATLAB: How to display string of matrix in one edit text

Related Question