Conduct frequency analysis on all characters in a binary blob.

freq_analysis.py

#!/usr/bin/env python3
import os, sys

# Debug if you want to stop early in large files
DEBUG = False
COLUMNS = 4

def main():
    # Preload a dictionary with all characters
    table = {}
    table = {e:0 for e in range(256)}

    # Grab data from file
    data = open(sys.argv[1], 'rb').read()

    # Loop thru data and count
    if DEBUG: b = 0
    for c in data:
        table[c] += 1
        # Debug large files
        if DEBUG: 
            b += 1
            if b == 2000: break

    # print results
    for e in range(0,256,COLUMNS):
        print()
        for r in range(COLUMNS):
            # This formating will help the column output
            print('{:<3s} {:>4s} {:>4d}'.format(hex(e+r),repr(chr(e+r)),table[e+r]), end = '')
            # Don't put the colon on the last column
            if r < (COLUMNS - 1): print(' : ',end = '')
    print()

if __name__ == '__main__':
    main()