On 2013-12-16 14:19, Djoser wrote: > I am new to this forum and also to Python, but I'm trying hard to > understand it better.
Welcome aboard! > I need to create a binary file, but the first 4 lines must be in > signed-Integer16 and all the others in signed-Integer32. I have a > program that does that with Matlab and other with Mathematica, but > I'm converting all for Python. You seem to be conflating ideas here: a binary file doesn't really have "lines". Do you mean "first 4 bytes"? If so, then a signed-Integer16 really only occupies 2 bytes, so you'd have to pad it somehow. That said, I suspect that the "struct" module will get you what you want: from struct import pack header16bit = 31415 data = list(range(10)) with open('output.bin', 'wb') as f: f.write(pack('h', header16bit)) for signed_32bit_number in data: f.write(pack('i', signed_32bit_number)) f.write(other_stuff) You might need to specify the byte-ordering, which you can do by prefixing the "h" or "i" with ">", "<" or "=" s documented at [1] -tkc [1] http://www.python.org/doc//current/library/struct.html . -- https://mail.python.org/mailman/listinfo/python-list