Euclidean distance for 3D data

Hye, can anybody help me, what is the calculation to calculate euclidean distance for 3D data that has x,y and z value in Matlab? Thank you so much. Really appreciate if somebody can help me.

[KSSV]

Read about dist. You can write your own formula for this not a deal.

[Jan]

The distance to what?

[Lu Zhang]

Hi, Nurul. Did you figure it out finally? Is it possible for you to share the answer? I want to compute the euclidean distance for fMRI data on the vertex level. Thank you so much.

Answer 1

[Jan]

I guess, that you want the distance of a set of points to a specific other point:

% 100 points in 3D:
Pos = rand(100, 3);

% Euclidean distance to point [1,2,3]:
D = sqrt(sum((Pos - [1,2,3]).^2, 2))

With modern Matlab versions:

D = vecnorm(Pos - [1,2,3], 2, 2)

With old Matlab versions before the auto-expanding (< R2016):

V = bsxfun(@minus, Pos, [1,2,3]);
D = sqrt(sum(V.^2, 2))

[Nurul Atifah]

I had try using the last code you give. And it can calculate my data. I just want to know is it wrong if im using out = squareform(pdist(A)) ? This is to calculate the face point distance between point to another point.

[Jan]

pdist calculates the pairwise distances between all points of the set. Is this what you want? You still did not mention, which distance you want to obtain.

[Nurul Atifah]

I want to calculate distance between a set of points to another set of points. Let say I have 83 x 3 points. I want to calculate the euclidean distance of the points. Did my explaination is well enough? Sorry if im bad at explaining. I will try my best. Btw, thank you for helping me.

[Jan]

No, this is still not clear. In the first sentence you mention two different sets of points. Afterwards you tell us, that one set is [83 x 3]. And the other set? I've posted the code for calculating the distances between a set of points and one additional point. With a simple loop, you can expand this to two sets.

[Nurul Atifah]

Sorry for my bad explaining. Okay, to have better view. I would like to calculate the euclidean distance as follows:

Eg,

x y z

3 4 5 --> 1st point

7 8 9 --> 2nd point

Therefore, I want to calculate between 1st point and 2nd point.

[Jan]

M    = [3,4,5; ...
        7,8,9];
v    = M(1, :) - M(2, :);
dist = sqrt(sum(v .^ 2))

[Nurul Atifah]

Ohh I see. Thats exactly what I want. Thank you so much. :)

[Dee]

Hi Nurul were you able to find for 83 by 3 matrix?

Answer 2

[dmitry luchinsky]

why not to use pdist2?