Created
January 10, 2020 12:22
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class NGram: | |
def __init__(self, order): | |
self.order = order | |
self.buffer = [] | |
def add(self, element): | |
tmp = None | |
if not element: | |
return tmp | |
if len(self.buffer) == self.order * 2: | |
tmp = self.buffer.pop(0) | |
if type(element) == list: | |
self.buffer.append(element) | |
else: | |
self.buffer.append([element, 1]) | |
self.analyse() | |
return tmp | |
def analyse(self): | |
tmp = [c[0] for c in self.buffer] | |
if tmp[0:self.order] == tmp[self.order:]: | |
for i in range(self.order): | |
self.buffer[i][1] += self.buffer[i+self.order][1] | |
self.buffer = self.buffer[0:self.order] | |
class Compressor: | |
def __init__(self, level): | |
self.level = level | |
self.ngrams = [ NGram(i) for i in range(1,level+1) ] | |
self.final = [] | |
def add(self, element): | |
head, tail = (self.ngrams[0], self.ngrams[1:]) | |
out = head.add(element) | |
for t in tail: | |
out = t.add(out) | |
if out: | |
self.final.append(out) | |
def flush(self): | |
for i in range(len(self.ngrams)): | |
current_buffer = self.ngrams[i].buffer | |
for out in current_buffer: | |
for u in range(i+1, len(self.ngrams)): | |
out = self.ngrams[u].add(out) | |
if out: | |
self.final.append(out) | |
if __name__ == '__main__': | |
import logging | |
LOGGING_FORMAT = '[%(levelname)s] [%(asctime)s] %(funcName)s(): %(message)s' | |
logging.basicConfig(level=logging.INFO, format=LOGGING_FORMAT) | |
logger = logging.getLogger() | |
t0 = [ | |
'0', '1', '2', '2', '2', '2', \ | |
'0', '1', '2', '2', '2', '2' | |
] | |
comp = Compressor(5) | |
logger.info('[+] Original buffer: {}'.format(t0)) | |
for c in t0: | |
comp.add(c) | |
comp.flush() | |
logger.info('[+] Compressed list: {}'.format(comp.final)) | |
size_before = len(t0) | |
size_after = len(comp.final) | |
logger.info('[+] Compression rate: {:.2f}%'.format(100.0 - (size_after * 100 / size_before))) |
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