python.compressB64 Namespace Reference

Functions
	_toB64 (n)
	_fromB64 (s)
	compressB64 (s)
	decompressB64 (s)

Variables
tuple	_B64_alphabet
str	s = "000010000000000010000001000000000001000000000010000001"
	c = compressB64(s)
	d = decompressB64(c)
	x = int(s, 2)
str	sx = "{:0X}".format(x)

Detailed Description

Encodes a bit string composed mostly by zeroes

Function Documentation

_fromB64()

python.compressB64._fromB64 ( s )

protected

Definition at line 21 of file compressB64.py.

def _fromB64(s):
    n = 0
    for i in range(0, len(s)):
        n *= 64
        n += _B64_alphabet.index(s[i])
    return n
 
 

_toB64()

python.compressB64._toB64 ( n )

protected

Definition at line 12 of file compressB64.py.

def _toB64(n):
    s = ""
    while n > 63:
        s = _B64_alphabet[n % 64] + s
        n = n//64
    s = _B64_alphabet[n % 64] + s
    return s
 
 

compressB64()

python.compressB64.compressB64

(

s

)

Encodes a string of zeroes and ones using a RLE method.

s is the string to encode.

Consecutive zeroes are encoded by its repetition count in Base64.
Ones are copied to output substituted by exclamation marks.

Example:
       input:   0001100001001101010000
       output:  D!!E!C!!B!B!E

Effective compression is only achieved when input is composed mostly
by zeroes.

The encoded string is returned.

Definition at line 29 of file compressB64.py.

def compressB64(s):
    """Encodes a string of zeroes and ones using a RLE method.
 
    s is the string to encode.
 
    Consecutive zeroes are encoded by its repetition count in Base64.
    Ones are copied to output substituted by exclamation marks.
 
    Example:
           input:   0001100001001101010000
           output:  D!!E!C!!B!B!E
 
    Effective compression is only achieved when input is composed mostly
    by zeroes.
 
    The encoded string is returned.
    """
 
    count = 0
    res = ""
    for k in range(0, len(s)):
        c = s[k]
        if c == '0':
            count += 1
        else:
            if count > 0:
                res += _toB64(count)
            res += "!"
            count = 0
 
    if count > 0:
        res += _toB64(count)
 
    return res
 
 

decompressB64()

python.compressB64.decompressB64

(

s

)

Decodes a string coded by compressB().

s is the string to decode.

The decoded string is returned.

Definition at line 65 of file compressB64.py.

def decompressB64(s):
    """Decodes a string coded by compressB().
 
    s is the string to decode.
 
    The decoded string is returned.
    """
 
    res = ""
    count = ""
    for k in range(0, len(s)):
        c = s[k]
        if c == "!" or c == " ":
            if len(count) > 0:
                res += "0" * _fromB64(count)
                count = ""
            res += c.replace("!", "1").replace(" ", "0")
        else:
            count += c
    if len(count) > 0:
        res += "0" * _fromB64(count)
 
    return res
 
 

Variable Documentation

_B64_alphabet

tuple python.compressB64._B64_alphabet

protected

Initial value:

=  ("ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                 "abcdefghijklmnopqrstuvwxyz"
                 "0123456789+/")

Definition at line 7 of file compressB64.py.

c

python.compressB64.c = compressB64(s)

Definition at line 93 of file compressB64.py.

d

python.compressB64.d = decompressB64(c)

Definition at line 94 of file compressB64.py.

s

str python.compressB64.s = "000010000000000010000001000000000001000000000010000001"

Definition at line 92 of file compressB64.py.

sx

str python.compressB64.sx = "{:0X}".format(x)

Definition at line 96 of file compressB64.py.

x

python.compressB64.x = int(s, 2)

Definition at line 95 of file compressB64.py.