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    Python读取实时数据流示例

    栏目:代码类 时间:2019-12-03 06:08

    1、#coding:utf-8

    chose = [
      ('foo',1,2),
      ('bar','hello'),
      ('foo',3,4)
    ]
    
    def do_foo(x,y):
      print('foo',x,y)
    
    def do_bar(s):
      print('bar',s)
    
    for tag,*args in chose:
      if tag == 'foo':
        do_foo(*args)
    
      elif tag == 'bar':
        do_bar(*args)
    
    line = 'nobody:*:-2:-2:Unprivileged User:/var/empty:/usr/bin/false'
    
    uname,*fields,homedir,sh = line.split(':')
    print(sh)
    from collections import deque
    def search(lines, pattern, history=5):
      previous_lines = deque(maxlen=history)
      for li in lines:
        if pattern in li:
          yield li, previous_lines
        previous_lines.append(li)
    
    
    # Example use on a file
    if __name__ == '__main__':
      with open(r'./somefiles.py') as f:
        for line, prevlines in search(f, 'python', 5):
          for pline in prevlines:
            print(pline, end='')
          print(line, end='')
          print('-' * 20)
    

    2、import heapq

    portfolio = [
    {'name': 'IBM', 'shares': 100, 'price': 91.1},
    {'name': 'AAPL', 'shares': 50, 'price': 543.22},
    {'name': 'FB', 'shares': 200, 'price': 21.09},
    {'name': 'HPQ', 'shares': 35, 'price': 31.75},
    {'name': 'YHOO', 'shares': 45, 'price': 16.35},
    {'name': 'ACME', 'shares': 75, 'price': 115.65}
    ]
    cheap = heapq.nsmallest(3, portfolio, key=lambda s: s['price'])
    expensive = heapq.nlargest(3, portfolio, key=lambda s: s['price'])
    print(cheap)
    print(expensive)

    3、读取流数据源

    如果数据是来自一个连续的数据源,我们需要读取连续数据,接下来

    我们介绍一个适用于许多真是场景的简单解决方案,然而它并不是通用的。

    操作步骤:

    在本节中我们将想你演示如何读取一个实时变化的文件,并把输入打印出来。

    import time
    import os
    import sys
    
    if len(sys.argv) != 2:
      print('>>sys.stderr,"请输入需要读取的文件名!"')
    
    filename = sys.argv[1]
    
    if not os.path.isfile(filename):
      print('>>sys.stderr,"请给出需要的文件:\%s\: is not a file" % filename')
    
    with open(filename,'r') as f:
      filesize = os.stat(filename)[6]
      f.seek(filesize)
      while True:
        where = f.tell()
        line = f.readline()
        if not line:
          time.sleep(1)
          f.seek(where)
        else:
          print(line)
    

    以上这篇Python读取实时数据流示例就是小编分享给大家的全部内容了,希望能给大家一个参考,也希望大家多多支持IIS7站长之家。