Matlab string manipulation

Question

I need help with matlab using 'strtok' to find an ID in a text file and then read in or manipulate the rest of the row that is contained where that ID is. I also need this function to find (using strtok preferably) all occurrences of that same ID and group them in some way so that I can find averages. On to the sample code:

ID list being input:
(This is the KOIName variable)
010447529
010468501
010481335
010529637
010603247......etc.

File with data format:
(This is the StarData variable)
ID>>>>Values

002141865 3.867144e-03  742.000000  0.001121  16.155089  6.297494  0.001677

002141865 5.429278e-03  1940.000000  0.000477  16.583748  11.945627  0.001622

002141865 4.360715e-03  1897.000000  0.000667  16.863406  13.438383  0.001460

002141865 3.972467e-03  2127.000000  0.000459  16.103060  21.966853  0.001196

002141865 8.542932e-03  2094.000000  0.000421  17.452007  18.067214  0.002490

Do not be mislead by the examples I posted, that first number is repeated for about 15 lines then the ID changes and that goes for an entire set of different ID's, then they are repeated as a whole group again, think [1,2,3],[1,2,3], the main difference is the values trailing the ID which I need to average out in matlab.

My current code is:

function Avg_Koi

N = evalin('base', 'KOIName');

file_1 = evalin('base', 'StarData');

global result;

for i=1:size(N)
[id, values] = strtok(file_1);
result = result(id);
result = result(values)
end

end

Thanks for any assistance.

What is "result"? You can't use the same word to identify both a variable and a function. And then you're using it for the id and the values. Huh? — dmm
– dmm, Commented Oct 11, 2013 at 18:07
Also, assuming evalin works on 'StarData' (and I'm not sure it will), file_1 would then not be a char variable, so you can't use strtok on it. Type "whos" (without quotes) to see your variables. — dmm
– dmm, Commented Oct 11, 2013 at 18:15
I'm having trouble understanding your question, but I'm pretty sure you want to use "load", not "evalin". Type "help load". You don't want to evaluate the expressions in KOIName and StarData (since there aren't any), you just want to load that data into Matlab variables you can manipulate. — dmm
– dmm, Commented Oct 11, 2013 at 18:20

Robert Seifert · Accepted Answer · 2013-10-13 22:09:43Z

You let us guess a lot, so I guess you want something like this:

load StarData.txt

IDs = { 010447529;
        010468501;
        010481335;
        010529637;
        010603247;
        002141865}

L = numel(IDs);
values = cell(L,1);

% Iteration through all arrays and creating an cell array with matrices for every ID
for ii=1:L;
    ID = IDs{ii};
    ID_first = find(StarData(:,1) == ID,1,'first');
    ID_last = find(StarData(:,1) == ID,1,'last');

    values{ii} = StarData( ID_first:ID_last , 2:end );
end

When you now access the index ii=6 adressing the ID = 002141865

MatrixOfCertainID6 = values{6};

you get:

0.0038671440    742     0.001121    16.155089   6.2974940   0.001677
0.0054292780    1940    0.000477    16.583748   11.945627   0.001622
0.0043607150    1897    0.000667    16.863406   13.438383   0.001460
0.0039724670    2127    0.000459    16.103060   21.966853   0.001196
0.0085429320    2094    0.000421    17.452007   18.067214   0.002490

... for further calculations.

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