Find Lines in Uploaded Files That Are Similar in Python
Summary: in this tutorial, you learn diverse means to read text files in Python.
TL;DR
The following shows how to read all texts from the readme.txt file into a cord:
with open up('readme.txt') as f: lines = f.readlines()
Code language: JavaScript ( javascript ) Steps for reading a text file in Python
To read a text file in Python, y'all follow these steps:
- First, open up a text file for reading by using the
open up()function. - Second, read text from the text file using the file
read(),readline(), orreadlines()method of the file object. - Third, close the file using the file
close()method.
1) open() function
The open() function has many parameters merely you lot'll exist focusing on the beginning two.
open(path_to_file, mode)
The path_to_file parameter specifies the path to the text file.
If the file is in the same folder as the programme, you but need to specify the name of the file. Otherwise, you need to specify the path to the file.
To specify the path to the file, you apply the forrad-slash ('/') fifty-fifty if you lot're working in Windows.
For example, if the file is readme.txt stored in the sample folder as the plan, yous demand to specify the path to the file as c:/sample/readme.txt
The style is an optional parameter. Information technology'due south a string that specifies the manner in which you want to open the file.
The following table shows available modes for opening a text file:
| Mode | Description |
|---|---|
'r' | Open up for text file for reading text |
'w' | Open a text file for writing text |
'a' | Open a text file for appending text |
For example, to open a file whose name is the-zen-of-python.txt stored in the aforementioned folder as the programme, you lot use the post-obit code:
f = open('the-zen-of-python.txt','r')
Code language: JavaScript ( javascript ) The open() function returns a file object which you will use to read text from a text file.
2) Reading text methods
The file object provides y'all with three methods for reading text from a text file:
-
read()– read all text from a file into a string. This method is useful if you have a small file and you want to dispense the whole text of that file. -
readline()– read the text file line by line and return all the lines as strings. -
readlines()– read all the lines of the text file and return them as a listing of strings.
3) close() method
The file that you open will remain open until you shut information technology using the close() method.
It'south important to close the file that is no longer in utilize. If you don't close the file, the program may crash or the file would exist corrupted.
The following shows how to call the close() method to close the file:
f .close()
Code language: CSS ( css ) To close the file automatically without calling the close() method, you use the with statement similar this:
with open up(path_to_file) as f: contents = f.readlines()
Lawmaking language: JavaScript ( javascript ) In practice, y'all'll use the with statement to shut the file automatically.
Reading a text file examples
We'll utilize the-zen-of-python.txt file for the demonstration.
The post-obit example illustrates how to use the read() method to read all the contents of the the-zen-of-python.txt file into a string:
with open('the-zen-of-python.txt') every bit f: contents = f.read() print(contents)
Code language: JavaScript ( javascript ) Output:
Beautiful is improve than ugly. Explicit is better than implicit. Simple is better than circuitous. ...
The following case uses the readlines() method to read the text file and returns the file contents equally a list of strings:
lines = [] with open up('the-zen-of-python.txt') as f: lines = f.readlines() count = 0 for line in lines: count += i print(f'line {count}: {line}')
Code language: JavaScript ( javascript ) Output:
line i: Beautiful is better than ugly. line 2: Explicit is better than implicit. line iii: Elementary is better than complex. ...
The following example shows how to use the readline() to read the text file line by line:
with open up('the-zen-of-python.txt') equally f: line = f.readline() while line: line = f.readline() print(line)
Code language: JavaScript ( javascript ) Output:
Explicit is improve than implicit. Unproblematic is improve than complex. Complex is better than complicated. ...
A more curtailed style to read a text file line by line
The open up() function returns a file object which is an iterable object. Therefore, you can use a for loop to iterate over the lines of a text file as follows:
with open('the-zen-of-python.txt') as f: for line in f: impress(line)
Code language: JavaScript ( javascript ) This is more concise mode to read a text file line by line.
Read UTF-viii text files
The lawmaking in the previous examples works fine with ASCII text files. However, if you're dealing with other languages such equally Japanese, Chinese, and Korean, the text file is not a simple ASCII text file. And it's likely a UTF-8 file that uses more than but the standard ASCII text characters.
To open up a UTF-8 text file, y'all need to pass the encoding='utf-eight' to the open() function to instruct it to expect UTF-8 characters from the file.
For the demonstration, you'll utilize the post-obit quotes.txt file that contains some quotes in Japanese.
The post-obit shows how to loop through the quotes.txt file:
with open('quotes.txt', encoding='utf8') every bit f: for line in f: impress(line.strip())
Code language: JavaScript ( javascript ) Output:
Summary
- Apply the
open()role with the'r'mode to open a text file for reading. - Use the
read(),readline(), orreadlines()method to read a text file. - Always close a file after completing reading information technology using the
close()method or thewithstatement. - Utilize the
encoding='utf-viii'to read the UTF-8 text file.
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Source: https://www.pythontutorial.net/python-basics/python-read-text-file/
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