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我正在用python编程但是我遇到了一个我无法解决的小故障！问题是当它在文本文件中打印出来时，它只打印整个输出的一行！否则它工作！请我需要帮助才能完成这项工作！

import sys, bz2, string, os
#instead of hardcoding filename, get it from arguments
#filename = os.getcwd()
filename = raw_input("Enter the path of bz2 document e.g. files/access_log-20130301.bz2: ")
print "Using file : " + filename
source_file = bz2.BZ2File(filename, "r") 
for line in source_file:
    #Extract the date and put into a variable 
    logdate = string.split(line)[3][1:12]
    #Extract movie name and put into variable movie
    movie = string.split(line)[6]
    #extract who read the movie username = 
    usernames = string.split(line)[2]
    #Only process the movie line if we have /media/movie in it. 
    if movie.find('media/movies') > 0:
        #Prints all things prosscesed
        print "User:" + usernames + " On:" +  logdate + " Was watching:"+ movie
        #p=open(filename+"record.txt", "w")
        fp=open(filename+"record.txt", "wb+")
        fp.write("User: " + usernames + " On: " +  logdate + " Was watching: "+ movie+" File from:"+filename+"\n")
sys.exit()
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2 回答 2

1

问题很可能是您每次要写入一行时都为该文件打开一个新的文件句柄，并且您没有先刷新输出。这里有两种可能的解决方案：

  1. for在主循环之前打开要写入的文件。这样，您将只有一个文件句柄，并且缺少刷新不会导致此行为。确保完成后关闭文件。（考虑使用with块，这将导致文件在块终止时自动关闭with open(filename + "record.txt", "wb+") as f:：）
  2. fp调用后立即关闭fp.write()，这将强制刷新任何缓冲的输出，至少刷新到内核 I/O 缓存。

我更喜欢选项 1，因为在这种情况下没有理由多次打开和关闭文件。（如果你在文件中写了很多行，这些打开/刷新/关闭循环最终会浪费很多时间！）

选项 1 看起来像这样：

import sys, bz2, string, os
#instead of hardcoding filename, get it from arguments
#filename = os.getcwd()
filename = raw_input("Enter the path of bz2 document e.g. files/access_log-20130301.bz2: ")
print "Using file : " + filename
with open(filename+"record.txt", "wb+") as fp:
    source_file = bz2.BZ2File(filename, "r") 
    for line in source_file:
        #Extract the date and put into a variable 
        logdate = string.split(line)[3][1:12]
        #Extract movie name and put into variable movie
        movie = string.split(line)[6]
        #extract who read the movie username = 
        usernames = string.split(line)[2]
        #Only process the movie line if we have /media/movie in it. 
        if movie.find('media/movies') > 0:
            #Prints all things prosscesed
            print "User:" + usernames + " On:" +  logdate + " Was watching:"+ movie
            #p=open(filename+"record.txt", "w")
            fp.write("User: " + usernames + " On: " +  logdate + " Was watching: "+ movie+" File from:"+filename+"\n")

# The with block has ended at this point, so the file will already be closed here.

sys.exit()
于 2013-04-12T18:33:09.810 回答
1

您正在循环内以写入模式打开输出文件。在主循环之外打开它一次。

完成后请务必关闭它。更好的是，这样写：

with open(filename + "record.txt", "wb+") as fp:
    for line in source_file:
        ...
        fp.write(...)

以便open上下文管理器随后为您关闭它。

于 2013-04-12T18:34:14.793 回答