python多进程读取大文件并统计词频

末蓝、 2022-06-17 11:21 169阅读 0赞

转自： [http://www.jianshu.com/p/7665545c970b][http_www.jianshu.com_p_7665545c970b]

## python2.7 运用multiprocessing模块的Pool 异步进程池，分段读取文件（文件编码为gbk），并统计词频，代码如下： ##

# wordcounter.py #!/usr/bin/env python # -*- coding: utf-8 -*- from __future__ import print_function, division, unicode_literals import sys, re, time, os import operator from collections import Counter from functools import reduce from multiprocessing import Pool, cpu_count from datetime import datetime from utils import humansize, humantime, processbar def wrap(wcounter, fn, p1, p2, f_size): return wcounter.count_multi(fn, p1, p2, f_size) class WordCounter(object): def __init__(self, from_file, to_file=None, workers=None, coding=None, max_direct_read_size=10000000): '''根据设定的进程数，把文件from_file分割成大小基本相同，数量等同与进程数的文件段， 来读取并统计词频，然后把结果写入to_file中，当其为None时直接打印在终端或命令行上。 Args: @from_file 要读取的文件 @to_file 结果要写入的文件 @workers 进程数，为0时直接把文件一次性读入内存；为1时按for line in open(xxx) 读取；>=2时为多进程分段读取；默认为根据文件大小选择0或cpu数量的64倍 @coding 文件的编码方式，默认为采用chardet模块读取前1万个字符才自动判断 @max_direct_read_size 直接读取的最大值，默认为10000000（约10M） How to use: w = WordCounter('a.txt', 'b.txt') w.run() ''' if not os.path.isfile(from_file): raise Exception('No such file: 文件不存在') self.f1 = from_file self.filesize = os.path.getsize(from_file) self.f2 = to_file if workers is None: if self.filesize < int(max_direct_read_size): self.workers = 0 else: self.workers = cpu_count() * 64 else: self.workers = int(workers) if coding is None: try: import chardet except ImportError: os.system('pip install chardet') print('-'*70) import chardet with open(from_file, 'rb') as f: coding = chardet.detect(f.read(10000))['encoding'] self.coding = coding self._c = Counter() def run(self): start = time.time() if self.workers == 0: self.count_direct(self.f1) elif self.workers == 1: self.count_single(self.f1, self.filesize) else: pool = Pool(self.workers) res_list = [] for i in range(self.workers): p1 = self.filesize * i // self.workers p2 = self.filesize * (i+1) // self.workers args = [self, self.f1, p1, p2, self.filesize] res = pool.apply_async(func=wrap, args=args) res_list.append(res) pool.close() pool.join() self._c.update(reduce(operator.add, [r.get() for r in res_list])) if self.f2: with open(self.f2, 'wb') as f: f.write(self.result.encode(self.coding)) else: print(self.result) cost = '{:.1f}'.format(time.time()-start) size = humansize(self.filesize) tip = '\nFile size: {}. Workers: {}. Cost time: {} seconds' print(tip.format(size, self.workers, cost)) self.cost = cost + 's' def count_single(self, from_file, f_size): '''单进程读取文件并统计词频''' start = time.time() with open(from_file, 'rb') as f: for line in f: self._c.update(self.parse(line)) processbar(f.tell(), f_size, from_file, f_size, start) def count_direct(self, from_file): '''直接把文件内容全部读进内存并统计词频''' start = time.time() with open(from_file, 'rb') as f: line = f.read() self._c.update(self.parse(line)) def count_multi(self, fn, p1, p2, f_size): c = Counter() with open(fn, 'rb') as f: if p1: # 为防止字被截断的，分段处所在行不处理，从下一行开始正式处理 f.seek(p1-1) while b'\n' not in f.read(1): pass start = time.time() while 1: line = f.readline() c.update(self.parse(line)) pos = f.tell() if p1 == 0: #显示进度 processbar(pos, p2, fn, f_size, start) if pos >= p2: return c def parse(self, line): #解析读取的文件流 return Counter(re.sub(r'\s+','',line.decode(self.coding))) def flush(self): #清空统计结果 self._c = Counter() @property def counter(self): #返回统计结果的Counter类 return self._c @property def result(self): #返回统计结果的字符串型式，等同于要写入结果文件的内容 ss = ['{}: {}'.format(i, j) for i, j in self._c.most_common()] return '\n'.join(ss) def main(): if len(sys.argv) < 2: print('Usage: python wordcounter.py from_file to_file') exit(1) from_file, to_file = sys.argv[1:3] args = { 'coding' : None, 'workers': None, 'max_direct_read_size':10000000} for i in sys.argv: for k in args: if re.search(r'{}=(.+)'.format(k), i): args[k] = re.findall(r'{}=(.+)'.format(k), i)[0] w = WordCounter(from_file, to_file, **args) w.run() if __name__ == '__main__': main()

# utils.py #coding=utf-8 from __future__ import print_function, division, unicode_literals import os import time def humansize(size): """将文件的大小转成带单位的形式 >>> humansize(1024) == '1 KB' True >>> humansize(1000) == '1000 B' True >>> humansize(1024*1024) == '1 M' True >>> humansize(1024*1024*1024*2) == '2 G' True """ units = ['B', 'KB', 'M', 'G', 'T'] for unit in units: if size < 1024: break size = size // 1024 return '{} {}'.format(size, unit) def humantime(seconds): """将秒数转成00:00:00的形式 >>> humantime(3600) == '01:00:00' True >>> humantime(360) == '06:00' True >>> humantime(6) == '00:06' True """ h = m = '' seconds = int(seconds) if seconds >= 3600: h = '{:02}:'.format(seconds // 3600) seconds = seconds % 3600 if 1 or seconds >= 60: m = '{:02}:'.format(seconds // 60) seconds = seconds % 60 return '{}{}{:02}'.format(h, m, seconds) def processbar(pos, p2, fn, f_size, start): '''打印进度条 just like: a.txt, 50.00% [===== ] 1/2 [00:01<00:01] ''' percent = min(pos * 10000 // p2, 10000) done = '=' * (percent//1000) half = '-' if percent // 100 % 10 > 5 else '' tobe = ' ' * (10 - percent//1000 - len(half)) tip = '{}{}, '.format('\33[?25l', os.path.basename(fn)) #隐藏光标 past = time.time()-start remain = past/(percent+0.01)*(10000-percent) print('\r{}{:.1f}% [{}{}{}] {:,}/{:,} [{}<{}]'.format(tip, percent/100, done, half, tobe, min(pos*int(f_size//p2+0.5), f_size), f_size, humantime(past), humantime(remain)), end='') if percent == 10000: print('\33[?25h', end='') # 显示光标 if __name__ == '__main__': import doctest doctest.testmod()

github地址： [https://github.com/williezh/linuxtools][https_github.com_williezh_linuxtools]  
可以直接：

git clone https://github.com/williezh/linuxtools

运行结果：

[willie@localhost linuxtools]$ python wordcounter.py test/var/20000thousandlines.txt tmp2.txt 
    20000thousandlines.txt, 100.0% [==========] 115,000,000/115,000,000 [06:57<00:00]
    File size: 109 M. Workers: 128. Cost time: 417.8 seconds

[http_www.jianshu.com_p_7665545c970b]: http://www.jianshu.com/p/7665545c970b
[https_github.com_williezh_linuxtools]: https://github.com/williezh/linuxtools