Read block of data into matlab array - matlab

Question

I have a data file look like the following
3 1.0 1.4 1.7
2 1.2 1.5
1 1.1
2 1.1 1.2
For each line, the first integer indicates the number of floating numbers in this line.
Now I want to load all the data into a single matlab array, and ignore first column, that is, I want to get a array like this
>>arr = [1.0, 1.4, 1.7, 1.2, 1.5, 1.1, 1.1, 1.2]
if for each line, we have same number of floating numbers, I can simply do it like this
>>arr = load datafile ;
>>arr = arr(:,2:end) ; %ignore the first column
>>arr = arr(:) ;
However, if we have different number of floating numbers in each line, it seems we cannot directly loaded the file into a matrix. Is there any simple way to accomplish this ?
Thank you.

Answer 1

First, let's read the numbers as strings:
C = textread('myfile.txt', '%s', 'delimiter', '\n');
The result is a cell-array of strings, so let's apply str2num on each cell to obtain numerical values:
C = cellfun(#str2num, C, 'Uniform', false);
Now let's discard the first element from each cell:
C = cellfun(#(x)x(2:end), C, 'Uniform', false);
Finally, we concatenate all values into one vector:
arr = [C{:}]
This is the complete code:
C = textread('test.txt', '%s', 'delimiter', '\n'); %// Read data
C = cellfun(#str2num, C, 'Uniform', false); %// Convert to numbers
C = cellfun(#(x)x(2:end), C, 'Uniform', false); %// Remove first values
arr = [C{:}]
arr =
1.0000 1.4000 1.7000 1.2000 1.5000 1.1000 1.1000 1.2000

Answer 2

An easy way to do this would be to just read the file line by line
fid = fopen('data.txt');
arr = [];
tline = fgetl(fid);
while (tline ~= -1)
temp = str2num(tline);
arr = [arr temp(2:end)];
tline = fgetl(fid);
end
You might also try using the loadcell function, though I didn't try it so I'm not positive it will work for you.