How do i send to a specific line in python?
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Improve Article Save Article View Discussion Improve Article Save Article Text files are composed of plain text content. Text files are also known as flat files or plain files. Python provides easy support to read and access the content within the file. Text files are first opened and then the content is accessed from it in the order of lines. By default, the line numbers begin with the 0th index. There are various ways to read specific lines from a text file in python, this article is aimed at discussing them. File in use: test.txt Method 1: fileobject.readlines() A file object can be created in Python and then readlines() method can be invoked on this object to read lines into a stream. This method is preferred when a single line or a range of lines from a file needs to be accessed simultaneously. It can be easily used to print lines from any random starting index to some ending index. It initially reads the entire content of the file and keep a copy of it in memory. The lines at the specified indices are then accessed. Example: Python3
Output
Method 2: linecache package The linecache package can be imported in Python and then be used to extract and access specific lines in Python. The package can be used to read multiple lines simultaneously. It makes use of cache storage to perform optimization internally. This package opens the file on its own and gets to the particular line. This package has getline() method which is used for the same. Syntax: getLine(txt-file, line_number) Example: Python3
Output : This is line 5. Method 3: enumerate() The enumerate() method is used to convert a string or a list object to a sequence of data indexed by numbers. It is then used in the listing of the data in combination with for loop. Lines at particular indexes can be accessed by specifying the index numbers required in an array. Example: Python3
Output This is line 1. This is line 8. This is line 12. IntroductionA common task in programming is opening a file and parsing its contents. What do you do when the file you are trying to process is quite large, like several GB of data or larger? The answer to this problem is to read in chunks of a file at a time, process it, then free it from memory so you can process another chunk until the whole massive file has been processed. While it's up to you to determine a suitable size for the chunks of data you're processing, for many applications, it's suitable to process a file one line at a time. Throughout this article, we'll be covering a number of code examples that demonstrate how to read files line by line. In case you want to try out some of these examples by yourself, the code used in this article can be found at the following GitHub repo.
Basic File IO in PythonPython is a great general-purpose programming language, and it has a number of very useful file IO functionality in its standard library of built-in functions and modules. The built-in
As demonstrated above, the
Once you have written or read all of the desired data in a file object, you need to close the file so that resources can be reallocated on the operating system that the code is running on.
Note: It's always good practice to close a file object resource, but it's a task that's easy to forget. While you can always remember to call
By simply using the
Either of these two methods is suitable, with the first example being more Pythonic. The file
object returned from the Note: For the remainder of this article we will be working with the text of the book The "Iliad of Homer", which can be found at gutenberg.org, as well as in the GitHub repo where the code is for this article. Let's start off with the
This code snippet opens a file object whose reference is stored in Running this code, you should see something like the following:
Though, this approach is crude and explicit. Most certainly not very Pythonic. We can utilize the Read a File Line-by-Line with readlines()The
Check out our hands-on, practical guide to learning Git, with best-practices, industry-accepted standards, and included cheat sheet. Stop Googling Git commands and actually learn it! This results in:
Now, although much better, we don't even need to call the Read a File Line-by-Line with a for Loop - Most Pythonic ApproachThe returned This is the shortest, most Pythonic approach to solving the problem, and the approach favored by most:
This results in:
Here, we're taking advantage of the built-in functionalities of Python that allow us to effortlessly iterate over an iterable object, simply using a
Applications of Reading Files Line-by-LineHow can you use this practically? Most NLP applications deal with large corpora of data. Most of the time, it won't be wise to read the entire corpora into memory. While rudimentary, you can write a from-scratch solution to count the frequency of certain words, without using any external libraries. Let's write a simple script that loads in a file, reads it line-by-line, and counts the frequency of words, printing the 10 most frequent words and the number of their occurrences:
The script uses the Finally, we print the top ten most common words. Typically, for this, you'd create a Bag of Words Model, using libraries like NLTK, though, this implementation will suffice. Let's run the script and provide our
This results in:
ConclusionIn this article, we've explored multiple ways to read a file line-by-line in Python, as well as created a rudimentary Bag of Words model to calculate the frequency of words in a given file. How do you go to a specific line in a file Python?Use readlines() to Read the range of line from the File
The readlines() method reads all lines from a file and stores it in a list. You can use an index number as a line number to extract a set of lines from it. This is the most straightforward way to read a specific line from a file in Python.
How do you write to a specific line of a text file in Python?Use file.. a_file = open("sample.txt", "r"). list_of_lines = a_file. readlines(). list_of_lines[1] = "Line2\n". a_file = open("sample.txt", "w"). a_file. writelines(list_of_lines). a_file. close(). How do you write to a line in Python?To write to a text file in Python, you follow these steps: First, open the text file for writing (or append) using the open() function. Second, write to the text file using the write() or writelines() method.
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Steps for writing to text files.. How do you skip to a specific line in Python?There are many ways in which you can skip a line in python. Some methods are: if, continue, break, pass, readlines(), and slicing.
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