How do i search for a text and make it into a matrix, to display as an image? Using Structure functions.

-Import the text file

-search for 'Samps/line:' & 'Number of lines:'

-Get the values(numbers) '512' & '243'.

-Convert the values to a 512 X 243 matrix

-Display it as a image.

[Walter Roberson]

Why bother using a structure function? You have several steps leading up to displaying as an image, but you have not defined anything to be "returned" or anything in particular that you would insert into a structure.

Answer 1

[Image Analyst]

I'd use fopen(), then fgetl(), strfind() to look for the strings, sscanf() or str2double() to extract numbers out of strings (lines of text), finally fclose() to close the file. Then use imshow() to show the image. You're a smart engineer, you can do it - give it a try before asking us. Consider it a challenge. If you really can' t figure it out, even after looking at the examples in the help, come back with what code you do have and we'll get it working.

Answer 2

[shane]

hi i'm trying to change this subfunction.

i want to use a structure function to replace the token method.

function [matrix] = Inputreader1(readbox,txtsearch)

%Set the text strings to search headers
txtsearch1 = '"\Samps/line:';
txtsearch2 = '"\Number of lines:';

%Set variables to signal string found to logical zero
foundStr1 = false;
foundStr2 = false;
foundStr3 = false;

%Create an empty matrix array
matrix = [];

%initialise default values
done_input = 0;
i = 1;
j = 1; 
row1 = 0;
row2 = 0;
y = 0;
token = 0;
r=0;
k=0;
%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%%%

%open file
fid = fopen(readbox, 'r');

while (done_input == 0)

      %read data from rows
      readrowdata = fgets(fid);
      k=1;
      % fgets returns -1 if file is invalid
      if (readrowdata == -1)
          done_input = 1;
      else

   if (foundStr1 == false) || (foundStr2 == false) || (foundStr3 == false) 

          % search the first text from the row
          searchResult1 = strfind(readrowdata, txtsearch1);
          emptyResult1 = isempty(searchResult1);

          %found first text
          if emptyResult1 == false

              %make sure row1 and row2 is empty
              if (row1 == 0) || (row2 == 0)

                  %Find token in the string
                  [token, row1] = strtok(readrowdata);

                  %convertion of row1 into integer
                  row1 = sscanf(row1,'%d');

                  %inform that the first text is found
                  foundStr1 = true;
              end
          end

%%%~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%%%
 %condition to execute searching of second text
 if (foundStr1 == true) && (foundStr2 == false)

       %Search second text from row
       searchResult2 = strfind(readrowdata,txtsearch2);
       emptyResult2 = isempty(searchResult2);

       if emptyResult2 == false

           if (row2 == 0)
              [token, remain] = strtok(readrowdata);
               [r,remain] = strtok(remain);
               [r,remain] = strtok(remain);
               [row2] = strtok(remain,'"');

               %convertion of row2 into integer
               row2 = sscanf(row2,'%i');

               %signal that second text is found
               foundStr2 = true;

           end
       end
   end
   %%%*****************************************************************%%%

   %Condition to execute searching of Height(nm)
   if (foundStr1 == true) && (foundStr2 == true) && (foundStr3 == false) 

       %search the text from the row
       searchResult3 = strfind(readrowdata, txtsearch);
       emptyResult3 = isempty(searchResult3);

       %Signal that text is found
       if emptyResult3 == false
           foundStr3 = true;
           k=0;
       end
   end

end

if (foundStr3 == true)&& (k==1) && (done_input==0)

if i<=row2
    if j<=row1

           matrix(i, j) = sscanf(readrowdata, '%f');
      else
        i=i+1;
        j=1;
         matrix(i, j) = sscanf(readrowdata, '%f');
      end

      j=j+1;

      end
        end

end
    end
end

[Image Analyst]

You posted this as an official "Answer" so it sounds like this is the code you got working, so that's good. Congratulations.

[shane]

Is there a structure function that i can use? because i have to replace this program in a structure function form.

[Image Analyst]

There is a function called struct(). Look it up in the help.

[shane]

I have troubles inputting the struct() function into my program. Can you help me with it? Thank you :)

[shane]

I have to edit this program and submit it by Thursday, but i'm really stucked.

[Image Analyst]

Perhaps this: http://blogs.mathworks.com/videos/2012/07/03/debugging-in-matlab/

Answer 3

[Walter Roberson]

textstr = fileread('text.txt');
perline = str2double( regexp(textstr, '(?:Samps/line:\s*)\d+', 'match') );
numlines = str2double( regexp(textstr, '(?:Number of lines:\s*)\d+',, 'match') );
nums = str2double( regexp( regexp(textstr, '(?:Height(nm)\n).*', 'match'), '\n', 'split') );
nums = reshape(nums, perline, numlines) .';    %assuming data is listed in row order in file

imagesc(nums);

outstruct = struct('perline', perline, 'numlines', numlines, 'cdata', nums);

[shane]

when i use:

nums = reshape(nums, perline, numlines) .';

It gives me an

Error using reshape Size arguments must be integer scalars.

How can i change it into an integer?

samps = sscanf(samps,'%d');

this doesn't work.

[Image Analyst]

Find out which one (perline, or numlines) is zero, negative, or has a fractional part, then fix it.

[shane]

how do i fix it? do i use int8?

[shane]

str2double returns me with NaN.

[Image Analyst]

I don't know - what are its values? Say, did you ever look at the debugging link I gave you? You should be able to do this simple kind of debugging, like setting breakpoints and checking variable values. Debugging via asking people takes hours and hours while doing it yourself is almost instant. You've already been at this task for 5 days.

[Walter Roberson]

perline_string = regexp(textstr, '(?:Samps/line:\s*)\d+', 'match');
numlines_string = regexp(textstr, '(?:Number of lines:\s*)\d+', 'match');
perline = str2double(perline_string);
numlines = str2double(numlines_string);
if isnan(perline)
  error( sprintf('Something went wrong calculating perline. The input string matched was |%s|\n', perline_string );
end
if isnan(numlines)
  error( sprintf('Something went wrong calculating numlines. The input string matched was |%s|\n', numlines_string );
end