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

text filetextscan

Hi I have a problem choosing what kind of tool to import data from a text file. The data looks something like this although the lines are like 4000 and
35,       0401-BA1,1,6,8,00000,0,01,053,50530,'Channel                 ',,
35,       0401-CB1,1,6,8,00000,0,01,051,50510,'Spillway                ',,
35,       0401-EB1,1,3,2,00052,0,01,051,50510,'RioGrande               ',,
35,       0401-FS1,1,6,8,00203,0,01,011,27340,'Spillway                ',,
35,       0401-MB1,1,6,8,00000,0,01,037,0    ,'Canal                   ',,
I used the fscanf , textscan but I don't understand how to tackle the spaces. for the second space is it like %15c ?? Also How do I switch to another line should I use /n? Please help me here guys. Thank you

Best Answer

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
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