MATLAB: Select specific elements in a cell

cellevenselectselectionunevenvector

Hello, this is a very frustrating problem for me

I am using a loop that reads text lines from a data file using fgetl , such a line could look like this (there are many lines):

60 233 24 53 26 53 234 32

And could continue forever. I am trying to create a vector of every 1st value and a separate vector for every 2nd value, which is possible, but the following elements come in pairs . To illustrate:

aline = a b e f e f e f e f e f e f e f ...
anotherline = a b e f e f e f e f e f e f ...
so on ...

I am trying to make a cell for the e and a separate cell for f values, but cannot 'select' them in order to do so. How can you do this? I have tried playing with rem(1:len,2) == 1 (len = length of vector) to select every "odd" or "even" number, but it doesn't work as u want it to, as you cannot do the following.

x = rem(1:25,2) == 0;
vector(x);

What am i missing?

Best Answer

Instead of reading the file line-by-line and "growing" the arrays incrementally, try something like

x=textread('filename');
WW=x(:,1);
DD=x(:,2);
tt=x(:,3:2:end);
CC=x(:,4:2:end);

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MATLAB: How to change cell array into strings

 cc = cellfun(@num2str,c,'uni',0)

if you have both string and numerics in cell array and you want to convert them all to char,

 cc = cell(size(c));
 for k=1:numel(c)
   if(isnumeric(c{k}))
       cc{k} = num2str(c{k});
   elseif (isstring(c{k}))
       cc{kk}= char(c{k});
   %and so on
   end
 end

Another idea is,

 cellfun(@(x) char(string(x)),c,'uni',0)

MATLAB: How to delete numeric Headings/Delimiters from a large text file

inFID     = fopen(FileName, 'r');
outFID    = fopen([FileName, '.fixed'], 'W');  % [EDITED: 'w' => 'W']
Delimiter = ',';  % Or whatever it is
Break     = char(10);
while ~feof(inFID)
  S = fgets(inFID);
  if length(findstr(S, Delimiter)) > 2
    fwrite(outFID, S, 'char');
    fwrite(outFID, Break, 'char');  % Linebreak
  end
end
fclose(inFID);
fclose(outFID);

Import each line. Export it only, if it is recognized as not belonging to the "numerical headings (1,3)". Maybe length(findstr(S, Delimiter)) > 2 is not optimal, so please post a short example of how the kind of lines can be distinguished.

By the way: "Massive" text files are nonsense. Text files are useful only, if they are read and edited by human, but this is impossible for huge data. Think of converting the data to a binary format, if you want to store a matrix only. This would be more efficient.

[EDITED 2] Do the lines to be kept start with a space? Then this might be faster:

S = fileread(FileName);
C = strsplit(S, char(10));
C = C(strncmp(C, ' ', 1));
fid = fopen([FileName, '.fixed'], 'W');
fprintf(fid, '%s\n', C{:});
fclose(fid)

Best Answer

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MATLAB: How to change cell array into strings

MATLAB: How to delete numeric Headings/Delimiters from a large text file

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