How to find a value in a file from the index of another array?

I have a data column with 7 columns. Based on column 1, 2 and 7 of the .txt file, I need to open my .dat file. Next, I need to find the value of the variable in the .dat file for the index (column 3 of the .txt file). How can I do this? This is a part of my .txt file:

20140101 0000 69760 -5.965 -36.250 26.0 02000
20140101 0000 69761 -5.974 -36.250 23.5 02000
20140101 0000 73180 -5.247 -36.187 23.5 02000
20140101 0000 73678 -5.229 -36.178 26.5 02000
20140101 0000 74178 -5.229 -36.169 26.5 02000
20140101 0000 128828 -6.576 -35.181 22.6 03000
20140101 0000 138373 -6.980 -35.009 20.8 02000
20140101 0000 139404 -7.259 -34.991 22.0 03000
20140101 0000 139904 -7.259 -34.982 23.0 03000
20140101 0000 140375 -6.998 -34.973 22.2 02000
20140101 0000 140404 -7.259 -34.973 24.5 03000
20140101 0000 140903 -7.250 -34.964 22.2 03000

[Walter Roberson]

The zeros are significant, I take it?

Are the field widths fixed for columns 2 and 7 ? By which I am asking if we can read it in as numeric, and then when we go to construct the file name, use the known fixed width with a %05d (for example) to get the proper leading zeros in place -- for example there would not be a field of 2000 that is intended to be distinct from a field of 02000 ?

[pink flower]

Yes, zeros are significant. The fields widths are fixed for columns 2 and 7. Always in column 2 there will be 4 digits and always in column 7 there will be 5 digits.

[Mohammad Sami]

I dont follow how you want to filter your data.

You can read it using textscan function.

fid = fopen('text.txt','r');
%data = textscan(fid,'%d %04d %d %f %f %f %05d');
data = textscan(fid,'%f %f %f %f %f %f %f');
fclose(fid);
data = table(data{:});

[Walter Roberson]

You should not use %0 format specifications for input.

Using a format width is not needed in this case, as the columns are well separated.

[Mohammad Sami]

thanks Walter.

Answer 1

[Walter Roberson]

datfiledir = 'appropriate directory';
txtdata = load('YourFile.txt');    %don't worry, it is all numeric

nrow = size(txtdata,1);
outputs = [];
for K = 1 : nrow
    key = txtdata(K,3);
    filename = fullfile(datfiledir, sprintf('%08d_%04d_%05d.dat'. txtdata(K, [1 2 7])));
    datdata = load(filename, '-ascii');
    [found, idx] = ismember(key, datdata(:,1));    %the 1 needs to be adjusted according to the dat format
    if found
        outputs(K,:) = datdata(idx,:);
    else
        outputs(K,:) = nan(1,size(datdata,2));
        fprintf('Warning: key %d not found for row %d in file "%s"\n', key, K, filename);
    end
end

[pink flower]

I got this error.

"Error using load

Number of columns on line 2 of ASCII file /home/amanda/Documentos/CODIGOS_RADAR/DADOS_ZDR/2014/jan2014/ZDR_02000_20140101_0000.dat must be the same as previous lines."

The .dat file is a 500 x 500 matrix. How can I use fopen to open it?