I have a binary string in ascii that I want to convert to raw binary in Python

Question

First things first, I've looked around and found this:

In python, how to convert a hex ascii string to raw internal binary string?

https://docs.python.org/3/library/base64.html

Which is nice, but seems to involve converting hexadecimal to a binary representation. And base64 doesn't seem to support what I want, or am I being silly?

What I have is code from Matlab that outputs data in the form of 16 bit signed binary. But it should be saved as a raw binary, and not .m. So I've pushed it to a .txt file. And thus it lives its life as ASCII, which is nice and all but I need it as a pure .bin.

I've tried being lazy about this and searched for tools to simply let me copy and paste my data over to a dummyfile. But for whatever reason I've failed that.

So fine fine, I could write a python code that opens up the data and chunks the data into 16bit blocks some logic code and write it as it's ACII implementation, then do a (https://docs.python.org/2/library/binascii.html) conversion and write to the file?

This seems horribly cludgy (probably because it is). How can I get about this in a more elegant, or more preferably, lazy manner?

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Short version: I have data like 0000111001000011 (signed 16) in ASCII encoding, I want that to be 0000111001000011 in raw bin. Me dumb, need help.

Answer 1

use int(string,base) with your input string and base 2 for binary data.

a = int('0000111001000011',2)

where a will be 3651

now you can write it to a file using the python struct

import struct   
outString = struct.pack('i',a) # i for signed int 16bit, 
                               # for others check the documentation

f = open('outfile','w')
f.write(outString)
f.close()

Answer 2

It seems you want to write 16-bit binary raw from Matlab?

Just use the 'fwrite' command in matlab, e.g.

fid=fopen('mybinaryfile.bin','wb')
fwrite(fid,data,'uint16')
fclose(fid)

Answer 3

Thanks for the fwrite pointers. (OK, something that actually works this time) ed. nop, it doesn't do a raw binary write. It's some formatting going on...

Beware! Python and bytes likes to do formatting that will differ when using file.write(list_of_bytes). That caused me headaches trying to get around that before going back to the bitstring library and basically solving it in half a minute. sighs

The below code does what I want:

##Importing my needed tools
import bitstring

##Open the file with the data
data = open('Path\\data.txt');

##Read from the file
buffer = data.read();

##Convert the data to the proper format for transering
bin_list = bitstring.BitArray(bin = str(buffer));
b_array = bin_list.bin

##Create a c switch equivalent function of sorts, because of hex 
def cswitch(x):
    if ((x == '1') or (x == '2') or (x == '3') or (x == '4') or (x == '5') or (x == '6') or (x == '7') or (x == '8') or (x == '9') or (x == '0') or (x == 'a') or (x == 'b') or (x == 'c') or (x == 'd') or (x == 'e') or (x == 'f')):
    x = {'1':'01', '2':'02', '3':'03', '4':'04', '5':'05', '6':'06', '7':'07', '8':'08', '9':'09', '0':'00', 'a':'0a', 'b':'0b', 'c':'0c', 'd':'0d', 'e':'0e', 'f':'0f'}[x];
        return x;
    else:
        return x;

#Create a "hexifier" function
def hexifier(x):
    x = bytes.fromhex( cswitch((hex ( int( x[:8],2) ) )[2:]) )
    return x;

##Init shenanigans
b2_array = bitstring.BitArray(hexifier(b_array));
b_array = b_array[8:];

##Prepare to write to mem in byte chunks by building a hex array
for i in range (0, 2**13-1):    
    #Format the data in byte sized chunks
    b2_array.append(hexifier(b_array));
    b_array = b_array[8:];

## Write to a file, using the format .write() likes
with open('path\\binary_data.bin', 'br+') as f:
        f.write(b2_array.bytes);

##Close the files   
data.close();   
f.close();