using strcat with num2str

I'm new to Matlab and I wanna know what does the below command or function means.

 filename = strcat(filename(1:(105-15)),num2str(i),'130')

Answer 1

[Walter Roberson]

You have

    filename='C:\X\fort.130';
    filename = strcat(filename(1:(105-15)),num2str(i),'130');

The first of those lines makes filename a string of 13 characters. The second of those lines tries to access the first 90 of those 13 characters.

Please have a look at

http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

Answer 2

[KSSV]

strcat - Concatenates strings in your code the strings are ...first 90 characters from the string filename, character i and number character 130.

num2str : converts number to string/ character.

[kareem salloomi]

Thanks Dr. Siva for your kind reply. Actually I have a data file with the extension of .130 its a fortran data file and I'm using the below matlab code to import these data. unfortunately, the command

filename = strcat(filename(1:(105-15)),num2str(i),'130')

is working properly and return the following error: "Index exceeds matrix dimensions".

clear all; close all; clc;
%%Initialize variables.
D=dir('C:\X\fort.*');
num=length(D(not([D.isdir])));
filename='C:\X\fort.130';

theta1=18;
theta2=42;
theta3=78;
theta4=102;
Phi_offset_F=120;
Phi_offset_S=240;

for i=1:1:num
    filename='C:\X\fort.130';
    filename = strcat(filename(1:(105-15)),num2str(i),'130');
    fprintf('%2f\n',i/num*100);
    delimiter = ' ';
    %%Read columns of data as strings:
    % For more information, see the TEXTSCAN documentation.
    formatSpec = '%s%s%s%s%s%s%s%[^\n\r]';

      %%Open the text file.
      fileID = fopen(filename,'r');

      %%Read columns of data according to format string.
      % This call is based on the structure of the file used to generate this
      % code. If an error occurs for a different file, try regenerating the code
      % from the Import Tool.
      dataArray = textscan(fileID, formatSpec, 'Delimiter', delimiter, 'MultipleDelimsAsOne', true,  'ReturnOnError', false);

      %%Close the text file.
      fclose(fileID);

      %%Convert the contents of columns containing numeric strings to numbers.
      % Replace non-numeric strings with NaN.
      raw = repmat({''},length(dataArray{1}),length(dataArray)-1);
      for col=1:length(dataArray)-1
          raw(1:length(dataArray{col}),col) = dataArray{col};
      end
      numericData = NaN(size(dataArray{1},1),size(dataArray,2));

      % Converts strings in the input cell array to numbers. Replaced non-numeric
      % strings with NaN.
      rawData = dataArray{2};
      for row=1:size(rawData, 1);
          % Create a regular expression to detect and remove non-numeric prefixes and
          % suffixes.
          regexstr = '(?<prefix>.*?)(?<numbers>([-]*(\d+[\,]*)+[\.]{0,1}\d*[eEdD]{0,1}[-+]*\d*[i]{0,1})|([-]*(\d+[\,]*)*[\.]{1,1}\d+[eEdD]{0,1}[-+]*\d*[i]{0,1}))(?<suffix>.*)';
          try
              result = regexp(rawData{row}, regexstr, 'names');
              numbers = result.numbers;

              % Detected commas in non-thousand locations.
              invalidThousandsSeparator = false;
              if any(numbers==',');
                  thousandsRegExp = '^\d+?(\,\d{3})*\.{0,1}\d*$';
                  if isempty(regexp(thousandsRegExp, ',', 'once'));
                      numbers = NaN;
                      invalidThousandsSeparator = true;
                  end
              end
              % Convert numeric strings to numbers.
              if ~invalidThousandsSeparator;
                  numbers = textscan(strrep(numbers, ',', ''), '%f');
                  numericData(row, 2) = numbers{1};
                  raw{row, 2} = numbers{1};
              end
          catch me
          end
      end

      %%Split data into numeric and cell columns.
      rawNumericColumns = raw(:, 2);
      rawCellColumns = raw(:, 1);

      %%Replace non-numeric cells with NaN
      R = cellfun(@(x) ~isnumeric(x) && ~islogical(x),rawNumericColumns);
      R2 = cellfun(@(x) ~isnumeric(x) && ~islogical(x),rawCellColumns);% Find non-numeric cells
      rawNumericColumns(R) = {NaN};
      rawCellColumns(R2)={NaN}; % Replace non-numeric cells
      x=length(rawCellColumns);
      %%Allocate imported array to column variable names
      The = cell2mat(rawCellColumns(:, 1));
      Timeaveraged = cell2mat(rawNumericColumns(:, 1));
      %Poyntine = rawCellColumns(:, 2);
      %vectorWmm = rawCellColumns(:, 3);
      %at = rawCellColumns(:, 4);
      %point = rawCellColumns(:, 5);

[James Tursa]

What does this print:

numel(filename)

Maybe filename doesn't have 105 characters.