Read Lines of a Text File R
Summary: in this tutorial, you lot larn various ways to read text files in Python.
TL;DR
The following shows how to read all texts from the readme.txt file into a string:
with open('readme.txt') equally f: lines = f.readlines()
Code language: JavaScript ( javascript ) Steps for reading a text file in Python
To read a text file in Python, you follow these steps:
- First, open 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() part
The open() role has many parameters but you'll be focusing on the first two.
open(path_to_file, mode)
The path_to_file parameter specifies the path to the text file.
If the file is in the aforementioned binder as the program, yous only 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 use the forward-slash ('/') even if yous're working in Windows.
For example, if the file is readme.txt stored in the sample binder equally the program, yous need to specify the path to the file as c:/sample/readme.txt
The mode is an optional parameter. It's a cord that specifies the mode in which yous want to open the file.
The following table shows available modes for opening a text file:
| Mode | Description |
|---|---|
'r' | Open 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 proper name is the-zen-of-python.txt stored in the same folder as the program, y'all use the following lawmaking:
f = open('the-zen-of-python.txt','r')
Lawmaking language: JavaScript ( javascript ) The open() part returns a file object which you will use to read text from a text file.
ii) 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 cord. This method is useful if you take a small file and you desire to manipulate the whole text of that file. -
readline()– read the text file line by line and return all the lines every bit 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 lot open volition remain open until you close information technology using the shut() method.
It's of import to close the file that is no longer in use. If you don't close the file, the plan may crash or the file would be corrupted.
The following shows how to call the shut() method to shut the file:
f .close()
Code language: CSS ( css ) To shut the file automatically without calling the close() method, you use the with statement like this:
with open(path_to_file) equally f: contents = f.readlines()
Code language: JavaScript ( javascript ) In exercise, you'll use the with statement to close the file automatically.
Reading a text file examples
We'll use the-zen-of-python.txt file for the sit-in.
The following example illustrates how to utilise the read() method to read all the contents of the the-zen-of-python.txt file into a string:
with open up('the-zen-of-python.txt') every bit f: contents = f.read() impress(contents)
Code language: JavaScript ( javascript ) Output:
Beautiful is ameliorate than ugly. Explicit is better than implicit. Unproblematic is amend than complex. ...
The post-obit example uses the readlines() method to read the text file and returns the file contents as a list of strings:
lines = [] with open up('the-zen-of-python.txt') every bit f: lines = f.readlines() count = 0 for line in lines: count += 1 print(f'line {count}: {line}')
Code language: JavaScript ( javascript ) Output:
line 1: Beautiful is better than ugly. line 2: Explicit is better than implicit. line iii: Simple is improve than complex. ...
The following example shows how to employ the readline() to read the text file line by line:
with open('the-zen-of-python.txt') as f: line = f.readline() while line: line = f.readline() print(line)
Code language: JavaScript ( javascript ) Output:
Explicit is improve than implicit. Simple is better than complex. Circuitous is better than complicated. ...
A more than curtailed way to read a text file line past line
The open() part returns a file object which is an iterable object. Therefore, you lot 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: print(line)
Code language: JavaScript ( javascript ) This is more concise style to read a text file line by line.
Read UTF-8 text files
The code in the previous examples works fine with ASCII text files. However, if you're dealing with other languages such every bit Japanese, Chinese, and Korean, the text file is not a simple ASCII text file. And information technology's likely a UTF-8 file that uses more just the standard ASCII text characters.
To open a UTF-viii text file, you need to pass the encoding='utf-8' to the open() function to instruct it to expect UTF-viii characters from the file.
For the demonstration, you'll use the following quotes.txt file that contains some quotes in Japanese.
The post-obit shows how to loop through the quotes.txt file:
with open up('quotes.txt', encoding='utf8') as f: for line in f: print(line.strip())
Code linguistic communication: JavaScript ( javascript ) Output:
Summary
- Use the
open up()function with the'r'mode to open a text file for reading. - Use the
read(),readline(), orreadlines()method to read a text file. - E'er close a file afterward completing reading it using the
close()method or thewithargument. - Apply the
encoding='utf-8'to read the UTF-8 text file.
Did you lot find this tutorial helpful ?
Source: https://www.pythontutorial.net/python-basics/python-read-text-file/
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