Distance between points in a table

Question

KK14 2020-11-15

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/648813-distance-between-points-in-a-table

回答： Adam Danz 2020-11-19

Hello all,

I have a table containing the (x,y) coordinates and I need to find the distance between each point and save it as an array. Could anybody please guide me?

Thanks in advance.

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Adam Danz 2020-11-16

or pdist2

KK14 2020-11-19

Hello,

I do not have access to the tool box. But anyways thanks for letting me know about 'pdist'.

BR

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Answer 1

Adam Danz 2020-11-19

0
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https://ww2.mathworks.cn/matlabcentral/answers/648813-distance-between-points-in-a-table#answer_550138

在 MATLAB Online 中打开

>I have a table containing the (x,y) coordinates and I need to find the distance between each point [without using pdist | pdist2]

Calculate distances row-wise

Create input table

rng('default')
T = array2table(rand(8,2).*10, 'VariableNames',{'X','Y'})
T = 8x2 table
      X         Y   
    ______    ______

    8.1472    9.5751
    9.0579    9.6489
    1.2699    1.5761
    9.1338    9.7059
    6.3236    9.5717
    0.9754    4.8538
     2.785    8.0028
    5.4688    1.4189

Add a column Dist that shows the distance between rows n and n-1.

T.Dist = [NaN; sqrt(diff(T.X).^2 + diff(T.Y).^2)]
T = 8x3 table
      X         Y        Dist  
    ______    ______    _______

    8.1472    9.5751        NaN
    9.0579    9.6489    0.91367
    1.2699    1.5761     11.217
    9.1338    9.7059     11.311
    6.3236    9.5717     2.8134
    0.9754    4.8538     7.1317
     2.785    8.0028      3.632
    5.4688    1.4189     7.1099

Calculate pairwise distances

Create input table

rng('default')
T = array2table(rand(8,2).*10, 'VariableNames',{'X','Y'})
T = 8x2 table
      X         Y   
    ______    ______

    8.1472    9.5751
    9.0579    9.6489
    1.2699    1.5761
    9.1338    9.7059
    6.3236    9.5717
    0.9754    4.8538
     2.785    8.0028
    5.4688    1.4189

Create square matrix of pairwise distances

[xi, yi] = meshgrid(1:numel(T.X), 1:numel(T.Y));
D = reshape(sqrt(diff(T.X([xi(:),yi(:)]),1,2).^2 + diff(T.Y([xi(:),yi(:)]),1,2).^2),size(xi))
D = 8×8
         0    0.9137   10.5490    0.9952    1.8236    8.5864    5.5880    8.5847
    0.9137         0   11.2171    0.0949    2.7354    9.3979    6.4853    8.9786
   10.5490   11.2171         0   11.3108    9.4588    3.2908    6.6029    4.2019
    0.9952    0.0949   11.3108         0    2.8134    9.4922    6.5732    9.0613
    1.8236    2.7354    9.4588    2.8134         0    7.1317    3.8708    8.1975
    8.5864    9.3979    3.2908    9.4922    7.1317         0    3.6320    5.6559
    5.5880    6.4853    6.6029    6.5732    3.8708    3.6320         0    7.1099
    8.5847    8.9786    4.2019    9.0613    8.1975    5.6559    7.1099         0
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