Generate mat-file containing a 2D array of doubles.

libMat.py

#!/usr/bin/env python3

import struct

miINT8 = 1
miINT32 = 5
miUINT32 = 6
miDOUBLE = 9
miMATRIX = 14
mxDOUBLE_CLASS = 6

def gen_header( description = "" ):
	description = "MATLAB 5.0 MAT-file " + description
	
	header = bytes( description, "utf-8" )
	if len( header ) < 116:
		header += struct.pack("B", 0) * (116 - len(header))
	
	
	header += struct.pack( "8B", *([0]*8) )
	
	header += struct.pack( ">H2s", 0x0100, bytes( "MI", "ascii" ) )
	
	return header
	
def encode_row( values ):
	out = struct.pack( ">II", miDOUBLE, len(values)*8 )
	out += struct.pack( ">%id" % len(values), *values )
	return out

def gen_array( values, name = "array" ):
	
	out = struct.pack( ">IIII", miUINT32, 8, mxDOUBLE_CLASS, 0 )
	out += struct.pack( ">IIII", miINT32, 8, len( values ), len( values[0] ) )
	
	padding = 8 - len( name )
	out += struct.pack( ">II", miINT8, len( name ) )
	out += bytes( name, "utf-8" )
	if padding > 0:
		out += struct.pack( "B", 0 ) * padding
	
	single_row = []
	for row in values:
		single_row.extend( row )
	out += encode_row( single_row )
	
	
	array_header = struct.pack( ">II", miMATRIX, len( out ) )
	
	return array_header + out
	

def generate_mat( values, name = "array", description = "" ):
	return gen_header( description ) + gen_array( values, name )


def write_mat( fname, values, name = "array", description = "" ):
	with open( fname, 'wb' ) as handle:
		handle.write( generate_mat( values, name, description ) )