Python - Turn a file content into a binary array

Question

File content:

40 13 123
89 123 2223
4  12  0

I need to store the whole .txt file as a binary array so that I can send it later to the server side which expects a binary input.

---

I've looked at Python's bytearray documentation. I quote:

Return a new array of bytes. The bytearray type is a mutable sequence of integers in the range 0 <= x < 256. It has most of the usual methods of mutable sequences, described in Mutable Sequence Types, as well as most methods that the bytes type has, see Bytes and Byte Array Methods.

My numbers are greater than 256, I need a bytearray data structure for numbers that are greater than 256.

Answer 1

you might use the array/memoryview approach

import array
a = array.array('h', [10, 20, 300]) #assume that the input are short signed integers
memv = memoryview(a)
m = memv.cast('b') #cast to bytes
m.tolist()

this then gives [10, 0, 20, 0, 44, 1]

Depending on the usage, one might also do:

L = array.array('h', [10, 20, 300]).tostring()
list(map(ord, list(L)))

this also gives [10, 0, 20, 0, 44, 1]

Answer 2

You can read in the text file and convert each 'word' to an int:

with open(the_file, 'r') as f:
    lines = f.read_lines()
    numbers = [int(w) for line in lines for w in line.split()]

Then you have to pack numbers into a binary array with struct:

binary_representation = struct.pack("{}i".format(len(numbers)), *numbers)

If you want these data to be written in binary format, you have to specify so when opening the target file:

with open(target_file, 'wb') as f:
   f.write(binary_representation)