MATLAB: Loop erasing random walk

for loopMATLABrandomvectorizing

Hi, I'm trying to find a fast way to detect loops in a vector. By loop I mean repetition of an integer and by loop erasing remove all integers between two occurrence of any integer For instance,

v=[3 1 4 6 7 9 1 22 87 33  35 36 37 35 34] should be equal to [3 1 22 87 33 35 34]

basically these are the nodes that I'm visiting in a graph and there may be loops. I just want to obtain a simple path (without loops). I found solutions but require "for" loops and I need this to be performant since it will be applied to every walk (100'000 walk of length up to 2'000 ). If anyone could help it will be greatly appreciated.

Best Answer

EDIT

V = v(:);
[a b n] = unique(V,'first');
[~, bl, nl] = unique(V,'last');
v1 = [b bl];
v1(abs(diff(v1,[],2)) < 100*eps,:) = [];
vv = min(v1(:)):max(v1(:));
idx = arrayfun(@(x)vv(vv>=v1(x,1) & vv<v1(x,2)),1:size(v1,1),'un',0);
V([idx{:}]) = []

removed typo

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MATLAB: I need to know how to sum to the values of a specific column (identified by an index that can vary) of a generic matrix, a given column vector. For instance, how i decrease by 1 all the values of a column in a matrix (the rest remains the same)

Your question is rather confusing, as you seem to pose two different questions. I address both of these below:

>> A = magic(10)
A =
    92    99     1     8    15    67    74    51    58    40
    98    80     7    14    16    73    55    57    64    41
     4    81    88    20    22    54    56    63    70    47
    85    87    19    21     3    60    62    69    71    28
    86    93    25     2     9    61    68    75    52    34
    17    24    76    83    90    42    49    26    33    65
    23     5    82    89    91    48    30    32    39    66
    79     6    13    95    97    29    31    38    45    72
    10    12    94    96    78    35    37    44    46    53
    11    18   100    77    84    36    43    50    27    59
>> col = 6;
>> sum(A(:,col)) % the sum of one column
ans =  505
>> A(:,col) = A(:,col)-1 % decrease all values in one column
A =
    92    99     1     8    15    66    74    51    58    40
    98    80     7    14    16    72    55    57    64    41
     4    81    88    20    22    53    56    63    70    47
    85    87    19    21     3    59    62    69    71    28
    86    93    25     2     9    60    68    75    52    34
    17    24    76    83    90    41    49    26    33    65
    23     5    82    89    91    47    30    32    39    66
    79     6    13    95    97    28    31    38    45    72
    10    12    94    96    78    34    37    44    46    53
    11    18   100    77    84    35    43    50    27    59

Best Answer

Related Solutions

MATLAB: I want to convert pixel values into image. how to do it , i dont want to show it as graph etc i want to show the original image.

MATLAB: I need to know how to sum to the values ​​of a specific column (identified by an index that can vary) of a generic matrix, a given column vector. For instance, how i decrease by 1 all the values ​​of a column in a matrix (the rest remains the same)

Related Question

MATLAB: I need to know how to sum to the values of a specific column (identified by an index that can vary) of a generic matrix, a given column vector. For instance, how i decrease by 1 all the values of a column in a matrix (the rest remains the same)