向后读取文件

正常读取文件时，从文件开头逐行读取内容。 但是有些情况下我们想先读取最后一行。 例如，文件中的数据底部有最新记录，需要先读取最新记录。 为了达到此要求，可使用以下命令安装所需的包以执行此操作。

pip install file-read-backwards

但是在向后读取文件之前，我们先逐行读取文件的内容，以便可以在向后读取后可以作比较。

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]

当我们运行上面的程序时，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.

向后读取行

现在要向后读取文件，这里使用上面已安装的模块 - file-read-backwards。

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

当运行上面的程序时，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.

可以按相反顺序验证已读取的行。

向后读取单词

我们也可以向后阅读文件中的单词。首先向后读取行，然后使用reverse()函数对其中的单词进行标记。 在下面的示例中，使用nltk模块将向后打印的单词标记形成为同一文件。

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)

执行上面示例代码，得到以下结果 -

['.', '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']