How to Read Text File in Javascript Line by Line
Summary: in this tutorial, you lot 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('readme.txt') equally f: lines = f.readlines()
Code linguistic communication: JavaScript ( javascript ) Steps for reading a text file in Python
To read a text file in Python, you follow these steps:
- First, open up a text file for reading past using the
open()function. - 2d, 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.
i) open() part
The open() role has many parameters but yous'll be focusing on the first ii.
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 program, you just demand to specify the name of the file. Otherwise, you lot demand to specify the path to the file.
To specify the path to the file, you use the forward-slash ('/') even if you're working in Windows.
For case, if the file is readme.txt stored in the sample folder as the programme, yous demand to specify the path to the file every bit c:/sample/readme.txt
The mode is an optional parameter. It's a string that specifies the fashion in which you want to open the file.
The following tabular array shows available modes for opening a text file:
| Mode | Clarification |
|---|---|
'r' | Open for text file for reading text |
'w' | Open a text file for writing text |
'a' | Open up a text file for appending text |
For example, to open up a file whose proper noun is the-zen-of-python.txt stored in the same folder as the program, y'all use the following code:
f = open('the-zen-of-python.txt','r')
Code linguistic communication: JavaScript ( javascript ) The open() function returns a file object which you will utilise to read text from a text file.
2) Reading text methods
The file object provides you with 3 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 modest file and you lot desire to manipulate the whole text of that file. -
readline()– read the text file line past line and return all the lines equally strings. -
readlines()– read all the lines of the text file and return them as a listing of strings.
iii) close() method
The file that you lot open will remain open until yous shut it using the close() method.
Information technology'south of import to shut the file that is no longer in use. If yous don't close the file, the program may crash or the file would be corrupted.
The following shows how to telephone call the close() method to close the file:
f .close()
Code linguistic communication: CSS ( css ) To close the file automatically without calling the close() method, you use the with statement like this:
with open(path_to_file) every bit f: contents = f.readlines()
Code language: JavaScript ( javascript ) In practice, yous'll use the with statement to close the file automatically.
Reading a text file examples
We'll utilize the-zen-of-python.txt file for the sit-in.
The following 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 up('the-zen-of-python.txt') as f: contents = f.read() print(contents)
Code language: JavaScript ( javascript ) Output:
Beautiful is better than ugly. Explicit is amend than implicit. Unproblematic is improve than complex. ...
The post-obit case uses the readlines() method to read the text file and returns the file contents as a list of strings:
lines = [] with open('the-zen-of-python.txt') equally f: lines = f.readlines() count = 0 for line in lines: count += i print(f'line {count}: {line}')
Code linguistic communication: JavaScript ( javascript ) Output:
line one: Cute is meliorate than ugly. line 2: Explicit is better than implicit. line 3: Simple is better than complex. ...
The post-obit example shows how to use the readline() to read the text file line past line:
with open('the-zen-of-python.txt') as f: line = f.readline() while line: line = f.readline() impress(line)
Code language: JavaScript ( javascript ) Output:
Explicit is better than implicit. Simple is better than complex. Complex is better than complicated. ...
A more concise way to read a text file line past line
The open up() function returns a file object which is an iterable object. Therefore, yous tin 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 curtailed way to read a text file line past 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 it'southward probable a UTF-8 file that uses more than simply the standard ASCII text characters.
To open a UTF-eight text file, y'all demand to pass the encoding='utf-8' to the open() function to instruct information technology to expect UTF-8 characters from the file.
For the sit-in, 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('quotes.txt', encoding='utf8') as f: for line in f: print(line.strip())
Code language: 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. - Always close a file after completing reading it using the
close()method or thewithstatement. - Apply the
encoding='utf-8'to read the UTF-eight text file.
Did you lot notice this tutorial helpful ?
Source: https://www.pythontutorial.net/python-basics/python-read-text-file/
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