Python - 倒读文件 - 菜鸟教程

简述

当我们通常读取一个文件时，内容是从文件的开头逐行读取的。但在某些情况下，我们可能想先阅读最后一行。例如，文件中的数据在底部有最新记录，我们想先读取最新记录。为了实现这一要求，我们使用以下命令安装所需的包以执行此操作。


pip install file-read-backwards

但是在反向读取文件之前，让我们逐行读取文件的内容，以便我们可以比较反向读取后的结果。


with open ("Path\GodFather.txt", "r") as BigFile:
    data=BigFile.readlines()
# Print each line
   for i in range(len(data)):
    print "Line No- ",i 
    print data[i]

当我们运行上述程序时，我们得到以下输出 -


Line No-  0
Vito Corleone is the aging don (head) of the Corleone Mafia Family. 
Line No-  1
His youngest son Michael has returned from WWII just in time to see the wedding of Connie Corleone (Michael's sister) to Carlo Rizzi. 
Line No-  2
All of Michael's family is involved with the Mafia, but Michael just wants to live a normal life. Drug dealer Virgil Sollozzo is looking for Mafia families to offer him protection in exchange for a profit of the drug money. 
Line No-  3
He approaches Don Corleone about it, but, much against the advice of the Don's lawyer Tom Hagen, the Don is morally against the use of drugs, and turns down the offer.
Line No-  4
This does not please Sollozzo, who has the Don shot down by some of his hit men. 
Line No-  5
The Don barely survives, which leads his son Michael to begin a violent mob war against Sollozzo and tears the Corleone family apart.

向后阅读行

现在要向后读取文件，我们使用已安装的模块。


from file_read_backwards import FileReadBackwards
with FileReadBackwards("Path\GodFather.txt", encoding="utf-8") as BigFile:
# getting lines by lines starting from the last line up
    for line in BigFile:
        print line

当我们运行上述程序时，我们得到以下输出 -


The Don barely survives, which leads his son Michael to begin a violent mob war against Sollozzo and tears the Corleone family apart.
This does not please Sollozzo, who has the Don shot down by some of his hit men. 
He approaches Don Corleone about it, but, much against the advice of the Don's lawyer Tom Hagen, the Don is morally against the use of drugs, and turns down the offer.
All of Michael's family is involved with the Mafia, but Michael just wants to live a normal life. Drug dealer Virgil Sollozzo is looking for Mafia families to offer him protection in exchange for a profit of the drug money. 
His youngest son Michael has returned from WWII just in time to see the wedding of Connie Corleone (Michael's sister) to Carlo Rizzi. 
Vito Corleone is the aging don (head) of the Corleone Mafia Family.

您可以验证是否以相反的顺序读取了这些行。

倒读单词

我们还可以向后读取文件中的单词。为此，我们首先向后阅读这些行，然后使用反向函数标记其中的单词。在下面的示例中，我们使用 package 和 nltk 模块从同一个文件中反向打印单词标记。


import nltk
from file_read_backwards import FileReadBackwards
with FileReadBackwards("Path\GodFather.txt", encoding="utf-8") as BigFile:
# getting lines by lines starting from the last line up
# And tokenizing with applying reverse()
    for line in BigFile:
        word_data= line
        nltk_tokens = nltk.word_tokenize(word_data)
        nltk_tokens.reverse()
        print (nltk_tokens)

当我们运行上述程序时，我们得到以下输出 -


['.', 'apart', 'family', 'Corleone', 'the', 'tears', 'and', 'Sollozzo', 'against', 'war', 'mob', 'violent', 'a', 'begin', 'to', 'Michael', 'son', 'his', 'leads', 'which', ',', 'srvives', 'barely', 'Don', 'The']
['.', 'men', 'hit', 'his', 'of', 'some', 'by', 'down', 'shot', 'Don', 'the', 'has', 'who', ',', 'Sollozzo', 'please', 'not', 'does', 'This']
['.', 'offer', 'the', 'down', 'trns', 'and', ',', 'drgs', 'of', 'se', 'the', 'against', 'morally', 'is', 'Don', 'the', ',', 'Hagen', 'Tom', 'lawyer', "'s", 'Don', 'the', 'of', 'advice', 'the', 'against', 'mch', ',', 'bt', ',', 'it', 'abot', 'Corleone', 'Don', 'approaches', 'He']
['.', 'money', 'drg', 'the', 'of', 'profit', 'a', 'for', 'exchange', 'in', 'protection', 'him', 'offer', 'to', 'families', 'Mafia', 'for', 'looking', 'is', 'Sollozzo', 'Virgil', 'dealer', 'Drg', '.', 'life', 'normal', 'a', 'live', 'to', 'wants', 'jst', 'Michael', 'bt', ',', 'Mafia', 'the', 'with', 'involved', 'is', 'family', "'s", 'Michael', 'of', 'All']
['.', 'Rizzi', 'Carlo', 'to', ')', 'sister', "'s", 'Michael', '(', 'Corleone', 'Connie', 'of', 'wedding', 'the', 'see', 'to', 'time', 'in', 'jst', 'WWII', 'from', 'retrned', 'has', 'Michael', 'son', 'yongest', 'His']
['.', 'Family', 'Mafia', 'Corleone', 'the', 'of', ')', 'head', '(', 'don', 'aging', 'the', 'is', 'Corleone', 'Vito']