Hello Dan,
> I am trying to head in a binary file that has a header and different
> character types. The array module apparently expects the typecode to
> be the same throughout. Here's what the file looks like:
>
> Byte number: type: value: purpose:
> 1-4 char "ver."
> 5-8 char "0001" version number
> 9-12 int 1, 2, 3, or 4 data type: 1=unsigned byte
> 2=unsigned short 3=32-bit integer 4=32-bit floating point
>
> 13-16 int x dimension, xdim
> 7-20 int y dimension, ydim
> 20-24 int z dimension, zdim
> 25-28 int xdim*ydim*zdim
>
> The rest of the file contains the data array of type in indicated in
> bytes 9-12.
>
> I have tried:
> import Numeric as N
> import array
> fileobj = open(myfile, mode='rb')
> s = array.array('f')
> s.read(fileobj, size)
> data = N.array(s, typecode=N.Int)
> fileobj.close()
>
> But the header must confuse things because I do get what I expect.
I'd use the struct module to read the header and then create an array
according to type.
Note: The code below is untested and without error checking.
from struct import struct
from array import array
from os.path import getsize
TYPES = { # Type of array
1 : "c",
2 : "H",
3 : "i",
4 : "f"
}
filesize = getsize(filename) # File size
fo = open(filename, "rb")
header = fo.read(12) # Read interesting header information
fields = unpack("ssssssssi", header)
fo.read(15) # Skip non-data header
a = array(TYPES[fields[-1]) # Create array
size = (filesize - 28) / a.itemsize # Size to read
a.read(fo, size) # Read to array
Also check that you don't have little/big endien problems.
HTH.
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Miki Tebeka <[EMAIL PROTECTED]>
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