How to remove duplicate nodes from generated path and segments inbetween?

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Xi Wen Lim
Xi Wen Lim 2016-3-24
编辑： Teja Muppirala 2016-3-29
I really need help on this. Been at it for a week.
I have a randomly generated path between nodes 1 to 25.
Initial generation: 1 6 7 2 1 6 7 8 9 4 3 2 1 6 7 12 11 16 21 22 23 24 19 20 25
I want to remove all repeated segments and nodes so based on this, the final path I want is:
(1, 6, 7, 12, 11, 16, 21, 22, 23, 24, 19, 20, 25)
How should I do this? Pls help.

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采纳的回答

Guillaume
Guillaume 2016-3-24
编辑：Guillaume 2016-3-29
Seems like you want to delete everything between the first and last occurrence of any identical digit:
path = [1 6 7 2 1 6 7 8 9 4 3 2 1 6 7 12 11 16 21 22 23 24 19 20 25];
while true
pathvalues = unique(path);
pathhist = histcounts(path, [pathvalues, Inf]);
duplicate = pathvalues(find(pathhist > 1, 1)); %find identical digit if isempty(duplicate)
break; %nothing left to remove, exit loop
end
occurences = path == duplicate;
path(find(occurences, 1) : find(occurences, 1, 'last')-1) = []; %delete 1st occurence and anything up to last occurence
end
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Xi Wen Lim
Xi Wen Lim 2016-3-29
Sorry I didn't see this message earlier.
Path = [1 2 3 4 5 6 16 26 27 17 16 26 36 46 56 57 58 59 69 79 78 77 67 57 47 46 45 55 54 64 65 75 85 84 83 93 94 95 85 84 94 93 83 82 81 91 92 82 72 73 83 84 74 64 65 75 76 66 65 55 45 46 36 26 27 17 18 8 9 19 18 17 27 28 38 39 40 50 60 59 58 48 38 37 47 48 58 57 56 66 67 77 87 86 76 75 85 86 87 97 98 99 89 88 78 79 80 70 60 50 40 30 29 39 38 37 36 35 45 46 47 37 36 26 16 15 14 24 23 22 12 2 3 4 5 15 14 4 3 2 12 22 23 13 14 15 25 26 36 46 56 57 67 77 78 68 69 70 60 59 69 70 80 90 89 88 98 97 87 88 78 77 76 66 67 77 78 68 67 57 47 48 49 59 69 70 80 90 100]
Guillaume
Guillaume 2016-3-29
编辑：Guillaume 2016-3-29
Oh, there was a big bug in the code where I found which value was duplicated. I've edited my answer to fix the bug.
The lines
pathhist = histcounts(path, [unique(path), Inf]);
duplicate = path(find(pathhist > 1, 1)); %find identical digit
have been changed to
pathvalues = unique(path);
pathhist = histcounts(path, [pathvalues, Inf]);
duplicate = pathvalues(find(pathhist > 1, 1)); %find identical digit

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更多回答（1 个）

Teja Muppirala
Teja Muppirala 2016-3-29
编辑：Teja Muppirala 2016-3-29
If you have R2015b or newer, there are built-in functions to do this. In particular, SHORTESTPATH.
path = [1 6 7 2 1 6 7 8 9 4 3 2 1 6 7 12 11 16 21 22 23 24 19 20 25];
N = numel(path);
G = sparse(path(1:end-1),path(2:end),1,N,N); %Make adjacency matrix
G = digraph(G);
pathOut = shortestpath(G, path(1), path(end),'Method','unweighted')
The answer is:
pathOut =
1 6 7 12 11 16 21 22 23 24 19 20 25

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