MATLAB: Textread formatting help

formattextread

I have an ascii file which contains hourly sea level data in the following format:

siteid Year Month Day Hour Level Level Level Level… etc.

cn 1965 1 1 0000-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999

Where the hour is either 1200 or 0000, and the following values are the hourly tidal level for the 12 hour period. I'm having trouble extracting the data as there are no delimiters, but the values are restrained to their own columns.

Example, for the 11th of december 1969. There is no delimiters between year, month and day.

cn 19691211 0000 170 410 720 960 1020 1050 990 870 810 810 840 1020

Is there a way to set the format so matlab reads the value that is present in a certain column range? Like columns 8:11 which represent year. Any help would be greatly appreciated.

Best Answer

Do you know the exact format, i.e. the length of each field? I assume you do!

Read the full line as a string

buf = textscan( fid, '%s', 'delimiter', sprintf( '\n' ) );

next extract the columns

col1 = buf{ :, ix1:ix2 };

something like this. I leave the exact handling of the cell array. And last convert to numeric.

- per

Related Solutions

MATLAB: Reading datasets from .txt

Well something like this:

filename='tmp.txt';
fid=fopen(filename,'r');
if (fid==-1)
  error('could not open %s for reading',filename);
end
nDataSet=fscanf(fid,'%d',1);
Data=cell(nDataSet,1);
for idx=1:nDataSet
    nLines=fscanf(fid,'%d',1);
    Data{idx}=fscanf(fid,'%f,%f',[2,nLines])';
end
fclose(fid);

You can access each data set using Data{dataSetNumber}. I generated some sample data set stored in a file called tmp.txt;(attached file). Here is the output.

>> Data{1}
ans =
      1.0000         0
      2.0000    0.9058
      3.0000    0.1270
      4.0000    0.9134
      5.0000    0.6324
>> Data{2}
ans =
      1.0000         0
      2.0000    0.9058
      3.0000    0.1270
      4.0000    0.9134
      5.0000    0.6324
      1.0000         0
      2.0000    0.9058
      3.0000    0.1270
      4.0000    0.9134
      5.0000    0.6324
>> Data{3}
ans =
      1.0000         0
      2.0000    0.9058
      3.0000    0.1270

If the input file really has ' at the begining and the end of the data then use the following code: (I have also attached tmp2.txt for you)

filename='tmp2.txt';
fid=fopen(filename,'r');
if (fid==-1)
  error('could not open %s for reading',filename);
end
nDataSet=fscanf(fid,'%d',1);
Data=cell(nDataSet,1);
for idx=1:nDataSet
    nLines=fscanf(fid,'%d',1);
    tmpVar=strsplit(fscanf(fid,'%s',nLines),'''')';
    Data{idx}=cell2mat(cellfun(@(c) str2num(c),tmpVar(2:end-1),'UniformOutput',false));
end
fclose(fid);

MATLAB: How to pick numbers in text file in matrix format

Simple and efficient:

opt = {'HeaderLines',1, 'CollectOutput',true, 'EndOfLine','>', 'WhiteSpace',' \n\r\t'};
fmt = [repmat('%f',1,21),'%*s'];
[fid,msg] = fopen('sample.txt','rt');
assert(fid>=3,msg)
C = textscan(fid,fmt,opt{:});
fclose(fid);

Giving:

>> C{1}
ans =
  Columns 1 through 7
   17.6980         0         0         0         0   17.6980         0
         0         0    8.7540         0   17.5090         0    8.7540
         0         0    6.7200         0    6.7200         0    6.7200
  Columns 8 through 14
         0         0   17.6980         0         0   17.6980         0
         0         0    8.7540         0         0    8.7540         0
    6.7200    6.7200         0         0         0    6.7200         0
  Columns 15 through 21
         0         0         0         0         0         0   29.2090
         0         0         0         0         0         0   47.4730
         0         0         0         0         0         0   59.6790

Best Answer

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MATLAB: Reading datasets from .txt

MATLAB: How to pick numbers in text file in matrix format

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