fgetl skipping empty lines and text lines

So i have some data with unknown number of lines. They contain the numbers 1 or -1, text or empty lines. How do i fgetl to obtain only the numbers(no empty lines and text lines) to store into a matrix? say for example my data is

1 1 -1 1 1 -1
1 -1 1 1 -1 1

sdasr
-1 1 1 1 -1 -1

where --- is an empty line, what should my loop look like using a while loop to extract just the 1s and -1s into the matrix in the correct row and column they come in? I am thinking about using a while loop to fgetl all the lines but don't know what condition to use. Thanks

NB: Edited using {}Code to reflect actual file format -- dpb

[dpb]

How many columns and are they regular? How large is the file? Unless it's huge it's probably simpler to read into memory and process from there but the specific tests are dependent on the format (other than empty lines are simple, of course).

[alexander li]

The data is unknown but there are 1s and -1s which i'm meant to extract and noise which im meant to ignore such as text characters and empty lines.

Answer 1

[dpb]

No looping needed...as long as the numeric values are regular (ie, same number of columns each record) as shown.

>> c=textread('alex.dat','%s','delimiter','\n','whitespace','')  % sample file
c = 
    '1 1 -1 1 1 -1'
    '1 -1 1 1 -1 1'
    ''
    'sdasr'
    '-1 1 1 1 -1 -1 '
>> A=str2num(char(c(~cellfun(@(x) all(isletter(x)),c))))
A =
     1     1    -1     1     1    -1
     1    -1     1     1    -1     1
    -1     1     1     1    -1    -1
>>

ADDENDUM

Above will fail if the string happens to have any digits in it; more robust would be two steps; first remove blank lines and then use any instead of all for the alpha test.

isstrprop might turn out useful here, too...

ADDENDUM 2 :)

IF were going to use a loop and fgetl here, I'd do it more like--

A=[];  % allocate accumulator array
while ~feof(fid)
  try
    A=[A;str2num(fgetl(fid))];
  catch
  end
end

[alexander li]

Okay so i have the matrix now how do i fprintf it to the command window while keeping each element in the same row and same column? Thanks

[dpb]

disp(A)

Answer 2

[Image Analyst]

Just put

textLine = fgetl(fid);
if isempty(textLine) || length(textLine) == 0
     continue; % Skip "empty" lines.
end
% Extract numbers from string.
[whatever, whatever] = sscanf(textLine, '%d,.......

into your loop.

[alexander li]

say for example my data is

1 1 -1 1 1 -1

1 -1 1 1 -1 1

-----

sdasr

-1 1 1 1 -1 -1

where --- is an empty line, what should my loop look like using a while loop to extract just the 1s and -1s into the matrix in the correct row and column they come in?