filter a matix column values

Hi

I have a matrix with X and Y values for a trajectory. Also, distance and speed values.

I want to make a criteria(filter) for my speed or distance column; then, I will take those ralated XY points and plot/scatter them with different color code.

(for example, I want to plot XY points which distance is >1.5 for them).

The second goal which I am not sure if it is possible, is to plot these points on a figure which I plotted all XY points.

Answer 1

[KSSV]

Let X,Y,D,V be your (x,y) locations, distance and velocity respectively.

figure
hold on
plot(X,Y,'r')
plot(X(D>1.5),Y(D>1.5),'.b')
legend('path','locations D>1.5')

Answer 2

[Bob Thompson]

The filtering can be accomplished using logic indexing. Plotting is simply a matter of storing the data separately and plotting again. For the example I am going to assume you have a 2D array, where the columns are in the following order: [X Y S D]

data = [X Y S D]; % Just assigning values, your initial data shouldn't look anything like this.

plot(data(:,1),data(:,2)) % Plot all X and Y points

red = data(data(:,4)>1.5,:); % Filter all results for distance > 1.5
hold on % Plot more than one thing on the previous figure
plot(red(:,1),red(:,2)) % Plot reduced data as a second line