how to save coordinates in a text file?

I've used ''inpolygon'' function and I want to save the red points in a txt file in form of 2 columns of x and y, for ex. :

-1.21 3.24

-1.56 3.52

how can I do that? I'm new to matlab :D

The inpolygon function:

B=readmatrix('points.txt');

xv=B(:,1)';yv=B(:,2)';

p=readmatrix('points1.txt');

xq=p(:,1)';yq=p(:,2)';

[in,on] = inpolygon(xq,yq,xv,yv);

[Rik]

You want to write numbers to a text file. You just used readmatrix to read numbers from a text file. If you were guessing instead of googling (or looking at the related functions listed at the bottom of the documentation page), what would your first try for a function be?

[youssef hany]

NO, that's not what I want. I used read matrix to read points from file and then I applied a function (inpolygon) that filters the input data, all I need is to save the filtered points in a text file @Rik

[William Rose]

@youssef hany, @Rik is offering a hint which sounds good to me. You said "that's not what I want", but since you want to "save the filtered points in a text file", @Rik is right (as usual).

Answer 1

[William Rose]

@youssef hany,

I do not see the matrix of selected points which you want to save. Maybe that is the problem. Here is an example:

N=100; %total number of points
xq=rand(N,1); yq=rand(N,1);
xv=[.5 .9 .5 .1 .5];
yv=[.1 .5 .9 .5 .1];
in=inpolygon(xq,yq,xv,yv);
plot(xq,yq,'bo',xq(in),yq(in),'rx',xv,yv,'--r');

a=[xq(in),yq(in)];
writematrix(a,'a.txt')

Try that. It should save the coordinates of the selected points as a 2-column text file.