hi everybody , i have a question please , if i have X=[1:10] and Y=[-5:5] and i want to have all the point of the plane (x,y) , what can i do in matlab to extract this point to use it

Asked by mina massoud

mina massoud (view profile)

on 25 Feb 2019
Latest activity Edited by Jan

Jan (view profile)

on 27 Feb 2019
Accepted Answer by James Tursa

X=[1:10];
Y=[-5:5];
for i=1:10
for j=1:10

Alex Mcaulley

Alex Mcaulley (view profile)

on 25 Feb 2019
Please be more clear, what do you want exactly?
Jan

Jan (view profile)

on 25 Feb 2019
I do not understand also, what "have point of the plane" means. Extract them from what?
BY the way: -5:5 is a vector already and you do not need the square brackets. And it has 11 elements, not 10.
mina massoud

mina massoud (view profile)

on 25 Feb 2019
first i need to thank you for responding on my question ,
i try now to be more clear
1) what i need is a column vector 2x1 where the first row is x and the second row is y
2) i need to repeat it to get all the point of the plane (x,y)
for example if X=[ 1 2 3 4 5 ]
Y=[ -5 -4 -3 -2 -1 0 1 2 3 4 5]
so (1,-5) (2,-5) (3,-5)(4,-5)(5,-5)
(1,-4) (2,-4) (3,-4)(4,-4)(5,-4)
(1,-3) (2,-3) (3,-3)(4,-3)(5,-3)
and so on till ..........................................(1,5) (2,5) (3,5)(4,5)(5,5)
so i need in a cartesian coordinate all the pointi (x,y) to use it in a certain iteration
so every cycle i need to extract a point (x,y) that is a column vector 2x1 where the first row is the point x and the second row is the point y to use it in a certain iteration
thank u very much

Release

R2018b

Answer by James Tursa

James Tursa (view profile)

on 25 Feb 2019
Edited by James Tursa

James Tursa (view profile)

on 25 Feb 2019

Does this do what you want?
[x,y] = meshgrid(X,Y);
result = [x(:),y(:)];
Then iterate over the rows of result.
Or you can just use your double for loop, and have
for i=1:numel(X)
for j=1:numel(Y)
point = [X(i),Y(j)];
etc.

mina massoud

mina massoud (view profile)

on 26 Feb 2019
i tried this code but it didnt work
clear all
clc
intx=10;
inty=10;
D_x=3000;
D_y=1000;
x=[0:intx:D_x];
y=[-D_y/2:inty:D_y/2];
k=0
TgT=zeros(length(x),length(y))
for i=1:length(x)
for j=1:length(y)
k=k+1
TgT(k,:)=[x(i),y(j)]
end
end
James Tursa

James Tursa (view profile)

on 27 Feb 2019
You didn't pre-allocate TgT to the dimensions I specified. You have this:
TgT=zeros(length(x),length(y))
But I have this:
tgt = zeros(numel(x)*numel(y),2);
Jan

Jan (view profile)

on 27 Feb 2019
@mina: "it didnt work" is not useful to explain a problem. Do you get an error message (than post a complete copy) or do the result differ from your expectation (then explain both).
clear all; clc is called "cargo cult programming": It does not help to solve any problem. All it does is to waste processing time here.
A simpler method instead of the loops:
x = 0:intx:D_x; % No need for brackets
y = -D_y/2:inty:D_y/2; % x and y are vectors already
nx = numel(x);
ny = numel(y);
TgT = [replem(x.', ny, 1), repmat(y.', nx, 1)];