Finding closest point to known coordinates

Hi,

I want to find a coordinate which has minimum distance to other coordinates,

For example;

I want to find a coordinate (a,b) which has minimum distance to coordinates given below

x y

1 2

1 4

3 2

4 2

[Stephan]

euclidian distance?

Answer 1

[Star Strider]

The minimum distance of a set of points is the Centroid (link), defined as the mean of the coordinates of the points:

xy = [1    2
      1    4
      3    2
      4    2];
  
minDist = mean(xy);

figure
plot(xy(:,1), xy(:,2), 'pg')
hold on
plot(minDist(1), minDist(2), 'rp')
hold off
grid
axis equal

Experiment toi get the result you want.

[Mehmet Volkan Ozdogan]

Thank you for the answer, but i also need to find which coordinate (input coordinate) is closest to calculated mean coordinate

[Star Strider]

As always, my pleasure.

Use the pdist2 (link) function:

[dist,idx] = pdist2(xy, minDist, 'euclidean', 'Smallest',1)

producing here:

dist =
      0.90139

idx =
     3

that being row 3: (3,2).

[Mehmet Volkan Ozdogan]

Thank you very much for the answer, I am sorry perhaps it is very easy but i am too new with matlab.

But how can i assign the coordinates in row 3 to a variable?

I mean i want to assign the closest point to a variable.

Thank you for your support again

[Star Strider]

As always, my pleasure.

Use the ‘idx’ value:

newVar = xy(idx,:)

producing:

newVar =
     3     2

[Mehmet Volkan Ozdogan]

Thank you again

Sincerely

[Star Strider]

As always, my pleasure.