unique values inside a matrix

Question

Michel tawil 2019-9-21

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https://ww2.mathworks.cn/matlabcentral/answers/481507-unique-values-inside-a-matrix

评论： Star Strider 2019-9-22

采纳的回答： Star Strider

Hello,

Assuming i have a matrix like this m=

1 30

1 20

2 30

2 28

... ...

i want it to be like this:

1 30

1 20

2 30

2 28

PS: THE MATRIX IS HUGE CONSISTING OF 11000 ROWS AND 9 COLUMNS

unique is not working since it has it's taking a unique value of all, for example if i apply it for the second column it will take 28 for 1 and not for 2

thank you in advance

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Answer 1

Star Strider 2019-9-21

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/481507-unique-values-inside-a-matrix#answer_392932

编辑：Star Strider 2019-9-21

在 MATLAB Online 中打开

Try this:

A = [1  30
20
20
20
30
28
28];
Out = unique(A, 'rows', 'stable')

producing:

Experiment to get different results.

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Star Strider 2019-9-21

在 MATLAB Online 中打开

Using uniquetol with your .mat file:

D = load('C.mat');
A = D.C(:,1:2)
[Out,ia,ic] = uniquetol(A, 0.1, 'ByRows',1)
OutStable = A(ia,:)

produces:

A =
  74
  73
  72
  70
  69
  67
  65
  63
  61
  58
  57
  55
  53
  51
  50
  49
  48
  47
  46
  45
  44
  43
  42
  42
  41
  41
  40
  40
  32
  31
  30
  30
  29
  28
  28
  27
  26
  26
  25
  24
  24
  23
  22
  21
  21
  20
  20
  20
  20
  20
  85
  84
  82
  80
  78
  77
  75
  73
  72
  71
  69
  68
  67
  66
  65
  63
  62
  61
  60
  58
  57
  56
  54
  53
  52
  51
  50
  49
  48
  47
  46
  45
  44
  44
  43
  42
  42
  41
  33
  33
  33
  32
  91
  89
  87
  85
  83
  80
  78
  75
OutStable =
  20
  30
  40
  50
  61
  72
  32
  42
  52
  62
  72
  82
  75
  85

Experiment to get the result you want.

Star Strider 2019-9-22

在 MATLAB Online 中打开

Sure!

The code changes to:

D = load('C.mat');
C = D.C;
[Out,ia,ic] = uniquetol(C(:,[1 2]), 0.1, 'ByRows',1);
OutStable = C(ia,:)

producing:

OutStable =
            1           20          568         28.4            1       27.719       63.087       27.719       63.087
            1           30          755        37.75            1       27.719       63.087       27.719       63.087
            1           40          810         40.5            1       27.719       63.087       27.719       63.087
            1           50          890         44.5            1       27.719       63.087       27.719       63.087
            1           61         1005        50.25            1       27.719       63.087       27.719       63.087
            1           72         1108         55.4            1       27.719       63.087       27.719       63.087
            2           32          784         39.2            1       27.719       63.087       27.719       63.087
            2           42          831        41.55            1       27.719       63.087       27.719       63.087
            2           52          904         45.2            1       27.719       63.087       27.719       63.087
            2           62          983        49.15            1       27.719       63.087       27.719       63.087
            2           72         1020           51            1       27.719       63.087       27.719       63.087
            2           82         1068         53.4            1       27.719       63.087       27.719       63.087
            3           75         1040           52            1       27.719       63.087       27.719       63.088
            3           85         1106         55.3            1       27.719       63.087       27.719       63.088

This is the shortg format option, since it’s easier to read (and post). The full precision remains internally.

Michel tawil 2019-9-22

编辑：Michel tawil 2019-9-22

Thank you!

Star Strider 2019-9-22

As always, my pleasure!

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Answer 2

Guillaume 2019-9-21

1
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https://ww2.mathworks.cn/matlabcentral/answers/481507-unique-values-inside-a-matrix#answer_392933

在 MATLAB Online 中打开

I'm not sure what you mean by unique is not working. You haven't explained the reasoning for going from your input to your output, but it does look like you want unique rows:

result = unique(m, 'rows')

With your demo data:

>> m = [
30
20
20 
20
30
28
28];
>> unique(m, 'rows')
ans =
  20
  30
  28
  30
>> unique(m, 'rows', 'stable')  %with stable to get the same order as your example
ans =
  30
  20
  30
  28

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Michel tawil 2019-9-21

i can use this and it works well but i lose the cotents of the other colums

M=unique(C(:,1:2),'rows','stable');

Michel tawil 2019-9-22

Thank you !

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unique values inside a matrix

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unique values inside a matrix

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