gettting Data from file

hey Guys, I am using the fileread command to open a (.dat-file) which has the following disinge

-31050  0.500000  1  255  1.000000  5.000000
1  1  1  31.146388  16  217.650000  J_055
2  2  512  377.706052  128  157.723000  J_015
3  3  1  1.000000  1  136.334000  I_043
4  4  8  109.402337  64  185.494000  J_022
5  5  8  137.383648  64  189.172000  J_023
...  ...     ...     ...             ...     ...             ...

the 1st line is the header of the file. Question; How can i get Values of 1 column ? Or of a specific field ?

[Max Müller]

 fid = fopen('name.dat');
 ReadFile = textscan(fid,'%f','HeaderLines',1)

now how can i convert it into an array?

[Michael Haderlein]

That should already result in an array. But you read all the file into one array. Most likely you rather want to use textscan(fid,'%d %*d %*d %*f %*d %*f %*s','headerlines',1);

Answer 1

[Michael Haderlein]

Do you want to get a whole line or a whole column?

Column:

>> fid=fopen('test.txt');
>> A=textscan(fid,'%d %d %d %f %d %f %s','headerlines',1);
>> A{3}

ans =

             1
           512
             1
             8
             8

Line:

A=textscan(fid,'%f %f %f %f %f %f %s','headerlines',1);
>> B=cell2mat(A(1:end-1));
>> B(3,:)
ans =

      3.0000    3.0000    1.0000    1.0000    1.0000  136.3340

[Max Müller]

Column.....Thanks a lot. It works....

Now can pls tell me how these (%f %f %f %f %f %f %s) things are named, so I can learn more about them....

[Michael Haderlein]

The percentage sign indicates that some value will follow. f means, the value is a float, d means decimal, s means string and so on. Setting a * between the % and the type will skip this column. Details are in the help to the functions which are supporting this notation, e.g. http://www.mathworks.com/help/matlab/ref/textscan.html?searchHighlight=textscan#inputarg_formatSpec

Answer 2

[Michael Haderlein]

I think fileread is not the best option in this case. If you want to read the entire file, either use importdata or dlmread. If you want to skip some columns (e.g. for memory issues), you can use textscan (skip columns with the %*... specifier).

If you want to replace a specific value, either read the data, replace by A(32,4)=42; and save again or (a bit more tricky to realize) open the file, move to the position where you want to change something (fseek), write the new data and close the file. But then you need to know exactly the position in the file.

Best regards,

Michael

[Max Müller]

Sorry,

i am new to matlab. I just want this table to a [5,7] Array, where I can type.....A{3} and get the whole line and not (Index exceeds matrix dimensions.)