MATLAB: Could someone please explain to me how to take characters from a text file and put it in MATLAB

cell arraycharactersfscanfsscanftext file

So I've tried using fscanf and sscanf to take a group of words and numbers and put them into a cell array. An example of what I want in the array is "Wind data AA0, #2". I am new to MATLAB, so I've had problems getting the words I see in my text file to MATLAB using the right code. Could someone give me an example of how this is done? My attempt:

>> fileid = fopen('myfile.txt'); 
>> a = fscanf(fileid,'%g %g',[35 inf]) % I need only to row 35 % don't understand "%g" part
>> a = a';  % I saw that I might need to transpose it
>> fclose(fid)

Best Answer

This code will read in the whole file (well, it works on your sample file):

fid = fopen('MLsensLiftStartexample.txt','rt');
hdr = fgetl(fid);
txt = fgetl(fid);
pos = ftell(fid);
N = numel(regexp(fgetl(fid),'[^\t]+','match'));
fmt = repmat('%s',1,N);
fseek(fid,pos,'bof');
C = textscan(fid,fmt,'Delimiter','\t');
fclose(fid);
C = horzcat(C{:});
N = str2double(C);

Have a look at the variable C: all of the data is there, and the equivalent numeric in N (where appropriate).

Related Solutions

MATLAB: Trying to delete lines that start with an alphabet on a text file

Use fopen, fgetl, fclose to read your file into a cell array and discard the lines you don't want. Or if you want to write a new file, use fopen, fprintf, fclose and write as your read:

fidi = fopen('somefile.txt', 'rt');
fido = fopen('newfile.txt', 'wt');
tline = fgetl(fidi);
while ischar(tline)
  if ~isempty(tline) && tline(1) >= '0' && tline(1) <= '9'
    %line to keep
    fprintf(fido, '%s\n', tline);
  end
  tline = fgetl(fidi);
end
fclose(fidi);
fclose(fido);

edit: forgot to read the next line!

MATLAB: Importing line-by-line from a text file

Hint

    str = '35,  0401-BA1,1,6,8,00000,0,01,053,50530,''Channel     '',,';
    fmt = '%d%s%d%d%d%d%d%d%d%d%s%s';
    cac = textscan( str, fmt               ...
                ,   'Delimiter'    , ','   ...
                ,   'CollectOutput', true  );

" how to tackle the spaces" &nbsp depends on how you want the spaces in the resulting string variable values
"line-by-line" &nbsp what exactly do you mean?

&nbsp

Addendum I

This illustrates an approach. However, due to various mismatches between the header row and the data rows the result is not useful.

    sas = cssm()

returns

    1x4000 struct array with fields:
        STATE_CODE_001
        STRUCTURE_NUMBER_008
        RECORD_TYPE_005A
        ROUTE_PREFIX_005B
        SERVICE_LEVEL_005C
        ROUTE_NUMBER_005D
        DIRECTION_005E
        HIGHWAY_DISTRICT_002
        COUNTY_CODE_003
        PLACE_CODE_004
        ....

where

    function    sas = cssm 
    ffs = 'c:\m\cssm\NM14.txt';
    fid = fopen( ffs );
    str = fgetl( fid );
    col_head_list = parse_header( str );
    sas = repmat( cell2struct( repmat({''},1,112), col_head_list(1:112), 2 ), 1,4000 ); 
    jj  = 0;
    while not( feof(fid) )
        str = fgetl( fid );
        buf = parse_data_row( str );
        jj  = jj + 1;
        sas(1,jj) = cell2struct( buf(1:112), col_head_list(1:112), 2 );
    end
    fclose( fid );
    end
    function    cac = parse_header( str )
        cac = strsplit( str, ',' );
        cac = strtrim( cac );
    end
    function    cac = parse_data_row( str )
        cac = strsplit( str, ',' );
        cac = strtrim( cac );
    end

&nbsp

Addendum II

I was fooled by the function, strsplit, which as default treats multiple delimiters as one. In my world that only applies to space. Anyhow, now I have fixed the function cssm.

Read the data to a structure

    >> sas=cssm;

find all bridges, which have STATUS_WITH_10YR_RULE equal to '2'.

    >> is_sw10yrEq2 = strcmp('2',{sas.STATUS_WITH_10YR_RULE});
    >> sum(is_sw10yrEq2)
    ans =
       324

there are 324 of them. List their building year

    >> {sas(is_sw10yrEq2).YEAR_BUILT_027}
    ans = 
      Columns 1 through 9
        '1915'   '1936'   '1928'   '1931'   '1920'   '1951'   '1933'   '1939'   '1939'
      Columns 10 through 18
        '1924'   '1931'   '1931'   '1931'   '1932'   '1932'   '1936'   '1937'   '1936'
      ....

where

    function    sas = cssm 
        ffs = 'c:\m\cssm\NM14.txt';
        fid = fopen( ffs );
        str = fgetl( fid );
        colhead_list = parse_header( str );
        n_colhead = length( colhead_list );
        sas = repmat( cell2struct                                   ...
                    (   repmat({''},1,n_colhead), colhead_list, 2 ) ...
                    ,   1,4000                                      ); 
        jj  = 0;
        while not( feof(fid) )
            str = fgetl( fid );
            buf = parse_data_row( str );
            jj  = jj + 1;
            sas(1,jj) = cell2struct( buf, colhead_list, 2 );
        end
        fclose( fid );
        sas(1,jj+1:end) = [];
    end
    function    cac = parse_header( str )
        cac = strsplit( str, ',', 'CollapseDelimiters',false );
        cac = strtrim( cac );
    end
    function    cac = parse_data_row( str )
        cac = strsplit( str, ',', 'CollapseDelimiters',false );
        cac = strtrim( cac );
    end

&nbsp

Addendum III

Caveat: I hardly used the new (couple of years old), data type table. Nevertheless, table is targeted at problems like yours and I think you should

use Import Data interactively to read from a file of format B (one header line, comma separated, varying width) to a table. Make sure to uncheck Multiple Delimiters as One and select table. I've tested; it worked fine.
spend time with the documentation of table instead of fighting file formats.

&nbsp

Addendum IV

It is straightforward to read the file of format B (one header line, comma separated, varying width) with textscan

    >> cac = cssm
    cac = 
        {3951x134 cell}

where

    function    cac = cssm 
        ffs = 'c:\m\cssm\NM14.txt'; % one header line, comma separated, varying width 
        fid = fopen( ffs );
        str = fgetl( fid );
        chl = strtrim( strsplit( str, ',', 'CollapseDelimiters',false ) );
        len = length( chl );
        frm = repmat( '%s', 1, len );
        cac = textscan( fid, frm, 'CollectOutput',true ); 
        fclose( fid );
    end

Best Answer

Related Solutions

MATLAB: Trying to delete lines that start with an alphabet on a text file

MATLAB: Importing line-by-line from a text file

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