How to read only the first term on the file.

Hi, I would know if someone can help me with this. In the file I have, I only need to read te first term of the second column, I mean, the total_x number. Anyone know how can I do that?

Thanks

[Geoff Hayes]

Moises - what is the format of the file? Is it a text file or binary? Please attach the file (or a small example) rather than a zip file.

[Moises Belda]

Sorry, but I couldn't upload the file if is not in .zip extension. The original file has a .dat extension.

Thanks

[Jan]

@Moises: The format of this file is not clear. .DAT is not a unique identifier for a specific file format. So please mention, how you have created this file.

[Moises Belda]

Someone send it to me. I only have to obtain what I mentioned above. But, couldn’t you open the .zip file? Maybe I can send it by mail or something like that.

Thanks

[per isakson]

Is this "the first term of the second column" ?

(-1.781235e-01 0.000000e+00 -2.780365e-09)

[Moises Belda]

No, just only -1.781235e-01. I only need this term of all columns.

Thanks

[Moises Belda]

I again,

Could you help me once more, please. In the previous question I needed the first term of the first row, but instead of that now I need the third term, how could I obtain them? I am a bit lost with all the %f and %s...

Thank you

Answer 1

[per isakson]

Try this

%%
ffs = 'h:\m\cssm\force.dat'; % change to your folder
fid = fopen( ffs, 'r' );
cac = textscan( fid, '%*f%s%*s%*s', 1, 'Headerlines',4, 'Delimiter','\t' ); 
fclose( fid );
total_x = sscanf( cac{1}{1}, '(%f %*f %*f)' );

and display the value

>> total_x
total_x =
     -0.17812     
     

In response to comment

Try this instead

%%
ffs = 'h:\m\cssm\force.dat'; % change to your folder
fid = fopen( ffs, 'r' );
cac = textscan( fid, '%*f%s%*s%*s', inf, 'Headerlines',4, 'Delimiter','\t' ); 
fclose( fid );
total_x = cellfun( @(chr) sscanf(chr,'(%f %*f %*f)'), cac{1} );

and check the result

>> whos total_x
  Name              Size              Bytes  Class     Attributes
  total_x      190978x1             1527824  double 

[Moises Belda]

Okay. I’ll try. But doing that will I only obtain the first value of the first row, right? I need the first term of all file, like this -0.17812 but of all rows.

Thanks

[Moises Belda]

Good morning,

I tried what you say but it doesn't work. Matlab say that there is an error using textscan. Invalid file definer. Use fopen to generate a valid file definer. I don't know if I have to change something or what is happening.

Thank you very much

[Walter Roberson]

The fopen() failed. Your filename is probably not an exact match for the content of ffs

[Moises Belda]

What do you mean?

Thanks

[per isakson]

Change this string

'h:\m\cssm\force.dat'

to the full file specification, Filespec, of force.dat on your system

[Moises Belda]

Okay. Now it's working. Thank you very much for your help

[Jan]

If it works, please select this as accepted answer.