Easy Python file feature-operations on Rows

1. Count lines of text

The most common is readlines.

>>> handler=open (' input_file.txt ') >>> lines=handler.readlines () >>> Lenoffile=len (lines )

However, if it is a text file more than 100m, the above method is basically determined to be very slow, even can not run

So, we need other ways.

1) using cycle count, introduce enumerate method

Note: Count is starting from-1

2) If we consider the problem of performance, we use other methods

Because text files are generally n/a newline characters, we can load part of the text and calculate how many line breaks are inside.

>>> Import codecs>>> count = 0>>> the_file = Codecs.open (' input_file.txt ', ' RB ', ' Utf-8 ') > >> Try:while (True):      buffer = the_file.read (8192*1024)      if not buffer:break    

2. Read a line (take small text for example)

We usually think of loops and then go to a line to stop and print

The above example can be encapsulated as a method:

But we have a much quicker approach:

We introduce Linecache, we get a line by Getline method, but we need to note: its number of rows is starting from 0

Right here, thank you.

------------------------------------------------------------------

Click to jump 0 basic python-Catalogue

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

Easy Python file feature-operations on Rows