How get row index of first and last appearance each unique cell element

Question

Mekala balaji 2018-10-12

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/423653-how-get-row-index-of-first-and-last-appearance-each-unique-cell-element

编辑： Bruno Luong 2018-10-12

采纳的回答： Bruno Luong

在 MATLAB Online 中打开

Hi,

I have below cell array, and I want to get the unique elements based on 2nd column.

MUY09KT00    TW00.00
MUY09KT00    TW00.00
MUY09KT00    TW00.00
MHJ09KT00    PW00.00
MHJ09KT00    PW00.00
LHJ09KT00    NPW00.00
LHJ09KT00    NPW00.00
LHJ09KT00    NPW00.00
in this case, the unique element first index are:
1
4
6
in this case, the unique element last index are:
3
5
8

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Answer 1

Bruno Luong 2018-10-12

1
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https://ww2.mathworks.cn/matlabcentral/answers/423653-how-get-row-index-of-first-and-last-appearance-each-unique-cell-element#answer_341077

编辑：Bruno Luong 2018-10-12

在 MATLAB Online 中打开

Make the output in the "stable" order:

 x = ["MUY09KT00"    "TW00.00"
  "MUY09KT00"    "TW00.00"
  "MUY09KT00"    "TW00.00"
  "MHJ09KT00"    "PW00.00"
  "MHJ09KT00"    "PW00.00"
  "LHJ09KT00"    "NPW00.00"
  "LHJ09KT00"    "NPW00.00"
  "LHJ09KT00"    "NPW00.00"]
[~,~,J] = unique(x(:,2)); % Based on the 2nd column
jump = find([true; diff(J); true]);
first = jump(1:end-1)
last = jump(2:end)-1
first =
       1
       4
       6
last =
       3
       5
       8

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Answer 2

Sean de Wolski 2018-10-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/423653-how-get-row-index-of-first-and-last-appearance-each-unique-cell-element#answer_341070

在 MATLAB Online 中打开

Unique is your friend:

x = ["MUY09KT00"    "TW00.00"
"MUY09KT00"    "TW00.00"
"MUY09KT00"    "TW00.00"
"MHJ09KT00"    "PW00.00"
"MHJ09KT00"    "PW00.00"
"LHJ09KT00"    "NPW00.00"
"LHJ09KT00"    "NPW00.00"
"LHJ09KT00"    "NPW00.00"]
[~,first] = unique(x(:,1), 'first')
[~,last] = unique(x(:,1), 'last')