[Tutor] reading binary files

[jadrifter]

On Mon, 2009-02-02 at 11:31 +0000, etrade.griffiths at dsl.pipex.com wrote:
> Hi
> 
> I am trying to read data from a file that has format
> 
> item_name  num_items  item_type  items ....
> 
> eg
> 
> TIME      1  0.0
> DISTANCE 10  0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
> TIME      1  1.0
> DISTANCE 10  1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
> 
> I can read this if the data are in ASCII format using
> 
>     in_file = open("my_file.dat","r")
>     data1 = in_file.read()
>     tokens = data1.split()
> 
> and then stepping through the resulting list but the data 
> also appear in the same format in a binary file.  I tried 
> converting the binary file to an ASCII file using
> 
>     ifile = open("my_file.dat","rb")
>     ofile = open("new_file.dat","w")
>     base64.decode(ifile, ofile)
> 
> but that gave the error "Error: Incorrect padding".  I imagine
> that there is a straightforward way of doing this but haven't
> found it so far.  Would be grateful for any suggestions!
> 
> Thanks
> 
> Alun Griffiths
> 
Honestly I'm not sure what you're asking for but in general for reading
binary data the I use the struct module.  Check it out in the
documentation.

John Purser