MATLAB: How to compare numeric strings

comparesimilaritystrings

have a problem to find the similarity of two patterns. I use LCS of this two pattern to represent their longest common part. For example given a pattern

P='012(32)231(43)'

and a pattern

Q='231(43)40(12)321'

their longest common sequence is

LCS(P,Q)= '0,1,2,3,4,(43)'

I want to find similarity of 106 strings in a cell array. The common elements are the number (0,1,2,3,4) or couples of number that both strings have (43). I have a lot of difficultes: I have no idea, I can do it. I have found in MATLAB functions like strcmp, strcmpi, strncmp, strncmpi, ismember but they are for strings of same size; I have thought about using regexp but I don't know how. I have read other questions about compare strings but none appears to address this problem. Can you give me suggestions?

Best Answer

http://www.mathworks.com/matlabcentral/fileexchange/24559-longest-common-subsequence

http://www.mathworks.com/matlabcentral/fileexchange/27460-string-subsequence-tools

Related Solutions

MATLAB: Optimize code: find longest common sequence of two strings

One thing you should be doing is using

[uTrajectory, ~, uTrajidx] = unique(Trajectory);

Now uTrajectory will be only the unique strings and uTrajidx will be a list the same size as Trajectory that tells you which entry in uTrajectory that each entry in Trajectory ended up as. There is no point in re-doing the LCS calculation between strings that have been done before: do the unique ones and then copy the results if you need to.

After that:

nTraj = length(uTrajectory);
EA = zeros(nTraj, nTraj);
WA = zeros(nTraj, nTraj);
for pairidx1 = 1 : nTraj - 1
    string1 = uTrajectory{pairidx1};
    P = length(string1);
    for pairidx2 = pairidx1 + 1 : nTraj
      string2 = uTrajectory{pairidx2};
      Q = length(string2);
      [D, dist, aLongestString] = LCS(string1, string2);
      nLCS = length(aLongestString);    %do not call the result LCS, that is the function name!
      RatioQ = nLCS/Q;
      RatioP = nLCS/P;
      % MSTP-Similarity Equal Average
      this_EA = (RatioP + RatioQ)/2;
      EA(pairidx1, pairidx2) = this_EA;
      EA(pairidx2, pairidx1) = this_EA;
      % MSTP-Similarity Weighted Average
      this_WA = (P*RatioP+Q*ratioQ)/(P+Q);
      WA(pairidx1, pairidx2) = this_WA;
      WA(pairidx1, pairidx2) = this_WA;
    end

Outputs are EA and WA, symmetric matrices of the ratios, one row (or column) for each unique string. You could expand that out to have duplicate entries or to be in the original order if you need to.

MATLAB: How to extract a number from a string array

"How can extract the first three digit value only so that I get a matrix that is 164 165 165"

With a simple application of regexp and str2double:

>> C = {'(164) - (165)','(165) - (166)','(165) - (166)'};
>> str2double(regexp(C,'\d{3}','match','once'))
ans =
   164   165   165

Best Answer

Related Solutions

MATLAB: Optimize code: find longest common sequence of two strings

MATLAB: How to extract a number from a string array

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