Generating empty interval of points

2015 1 14
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更新时间：2015 1 15
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0 个投票

Dear All,
I want to generate points in the interval [20,80] and have the interval [40,60] as an empty area. I wrote this code but I don't now how to complete it. I'd appreciate any help.
LB=20;UB=80;
x = LB+(UB-LB)*rand(50,1);
y =LB+(UB-LB)*rand(50,1);
if x>40 | x<60| y>40 | y<60;
[x]==0;[y]==0;
plot(x,y, '.')
but it gives an error.
Regards

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 采纳的回答

Star Strider
Star Strider 2015-1-14

0 个投票

This seems to work:
LB=20;UB=80;
x = LB+(UB-LB)*rand(50,1);
y = LB+(UB-LB)*rand(50,1);
idx = [((x > 40) & (x < 60)) | ((y > 40) & (y < 60))];
x(idx) = [];
y(idx) = [];
figure(1)
plot(x, y, '+')
grid
The ‘idx’ variable tests for the conditions and creates a logical vector then used to assign the elements of ‘x’ and ‘y’ to ‘empty’ rather than zero. The plot shows that there are no points in the area you want cleared.

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imola
imola 2015-1-14
Dear Star,
Thanks for you and for Roger for answer me, I realize that I didn't explain what I want exactly, forgave me both of you, with your code I got four areas of points separate of each other while I need a whole area of points and an empty area in the middle, is like an empty square inside a big square of points, so I tried to use
t = ((x<=40)||(x>=60)) && ((y<=40)||(y>=60));
but its wrong, could you please sorted to me.
Regards,
Imola.
Star Strider
Star Strider 2015-1-14
编辑：Star Strider 2015-1-14
@imola — Change only the ‘idx’ line in my code to:
idx = [((x > 40) & (x < 60)) & ((y > 40) & (y < 60))];
to get this plot:
Image Analyst
Image Analyst 2015-1-14
That does give an empty square in the 40-60 range. It relies on tossing out points that initially landed in there, so that the final number of points is most likely less than 50. Do you need exactly 50 points in there, or is it okay to get however many you end up with?
imola
imola 2015-1-15
Thanks Star, that's fine, it works perfectly .
Regards

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更多回答（1 个）

Roger Stafford
Roger Stafford 2015-1-14

0 个投票

Do this:
LB=20;UB=80;
x = LB+(UB-LB)*rand(50,1);
y = LB+(UB-LB)*rand(50,1);
t = ((x<=40)|(x>=60)) & ((y<=40)|(y>=60));
x = x(t);
y = y(t);
plot(x,y,'.')

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imola
imola 2015-1-14
Dear Roger, Thanks for you and for star for answer me, I realize that I didn't explain what I want exactly, forgave me both of you, with your code I got four areas of points separate of each other while I need a whole area of points and an empty area in the middle, is like an empty square inside a big square of points, so I tried to use
t = ((x<=40)||(x>=60)) && ((y<=40)||(y>=60));
but its wrong, could you please sorted to me.
Regards,
Imola.

请先登录，再进行评论。

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