% a concrete example file, with smaller matrices, is attached:
filename = 'test_file.txt';
% show the file's contents, for reference:
type(filename)
Here is one method that reads the entire file at once and interprets the matrices contained within.
- It is assumed that the line immediately following the last line that starts with '#Atoms' starts with a positive integer defining how many immediately subsequent lines contain the first matrix (as you describe).
- After the first matrix is read, the code continues to read matrices the same way (one line of text defining the number of rows in the matrix followed by that many lines of text containing the matrix).
- Matrices are stored in the cell array "result".
% read the file's contents into a character vector:
fid = fopen(filename,'r');
ch = fread(fid,[1 Inf],'*char');
fclose(fid);
% split on line endings (\n or \r\n):
str = regexp(ch,'\r?\n','split');
% number of lines of text in the file:
n_lines = numel(str);
% index of the line that immediately follows the last
% line in the file that starts with '#Atoms':
idx = find(startsWith(str,'#Atoms'),1,'last')+1;
% initialize the matrix counter:
ii = 1;
% go as long as idx does not exceed the number of lines in the file
% (idx indicates the line immediately before the next matrix to read (and
% immediately after the previously-read matrix, if any)):
while idx <= n_lines
% read line #idx to get the number of rows/lines in the next matrix:
num = sscanf(str{idx},'%d');
% matrix start and end line indices:
start_idx = idx+1;
end_idx = idx+num(1);
% section (i.e., consecutive lines of text) defining the matrix:
section = str(start_idx:end_idx);
% split those lines on whitespace to get the numbers
% (still in char form):
C = regexp(section,'\s','split');
C = vertcat(C{:});
% convert each char to double (numeric) and store the resulting
% matrix in the "result" cell array:
result{ii} = str2double(C);
% increment the matrix counter:
ii = ii+1;
% move to the next line after the matrix ends, and continue the loop
% (if more lines are left):
idx = end_idx+1;
end
% see the matrices:
disp(result)
result{:}
% if you really want to make two variables, one for each of the first two
% matrices in result:
M1 = result{1};
M2 = result{2};
Here is another method that interprets the matrix sections the same way as in the previous method, but it reads the file line-by-line (so it will work for larger files than the first method will), and it expects the matrix definitions to start immediately following the first '#Atoms' line (not the last as in the previous method).
% open the file:
fid = fopen(filename,'r');
% read lines one at a time until you get to the
% first line that starts with '#Atoms':
while ~feof(fid)
ch = fgetl(fid);
if startsWith(ch,'#Atoms')
break
end
end
% initialize the matrix counter:
ii = 1;
% continue until the end of the file:
while ~feof(fid)
% get the next line:
ch = fgetl(fid);
% read off the number of matrix rows expected to follow:
num = sscanf(ch,'%d');
% read that many lines into the cell array "section":
section = cell(num(1),1);
for jj = 1:num(1)
section{jj} = fgetl(fid);
end
% split those lines on whitespace to get the numbers
% (still in char form):
C = regexp(section,'\s','split');
C = vertcat(C{:});
% convert each char to double (numeric) and store the
% resulting matrix in the "result" cell array:
result{ii} = str2double(C);
% increment the matrix counter:
ii = ii+1;
end
% close the file:
fclose(fid);
% see the matrices:
disp(result)
result{:}
