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Python Articles
Page 790 of 855
How to make the argument optional in Python
Introduction..Sometimes, the programs require optional arguments when supplied will use them else go back to default declarations. We will see in this example on how to use them.The parameters that start with dashes (--) are identified as optional, so they can be left out, and they may have default values.Parameters that don’t start with dashes are positional and are usually required, so they do not have default values.How to do it...Exampleimport argparse parser = argparse.ArgumentParser(description='Optional Argument Example') parser.add_argument('-n', '--name', metavar='name', default='World', help='Say Hello to ') args = parser.parse_args() print(f"Hello {args.name}")The “metavar” will show up in the usage to describe the ...
Read MoreHow to combine multiple graphs in Python
IntroductionMatplotlib allows to add more than one plot in the same graph. In this tutorial, I will show you how to present data in the same plot, on two different axes.How to do it..1. Install matplotlib by opening up the python command prompt and firing pip install matplotlib.import matplotlib.pyplot as plt2. Prepare the data to be displayed.import matplotlib.pyplot as plt # data prep (I made up data no accuracy in these stats) mobile = ['Iphone', 'Galaxy', 'Pixel'] # Data for the mobile units sold for 4 Quaters in Million units_sold = (('2016', 12, 8, 6), ('2017', 14, 10, ...
Read MoreHow to match text at the start or end of a string in Python?
Problem..Assume you need to check the start or end of a string for a specific text patterns. The common patterns might be filename extensions but can also be anything. I will show you few methods on how you can do this.Startswith() methodA simple way to check the beginning of a string is by using startswith() method.Exampletext = "Is USA colder than Australia?" print(f"output {text.startswith('Is')}")OutputTrueExamplefilename = "Hello_world.txt" print(f"output {filename.startswith('Hello')}")OutputTrueExamplesite_url = 'https://www.something.com' print(f"output {site_url.startswith('http:')}")OutputFalseExampleprint(f"output {site_url.startswith('https:')}")OutputTrueendswith() Method.A simple way to check the ending of a string is by using endswith() method.Outputtext = "Is USA colder than Australia?" print(f"output ...
Read MoreHow to Search and Replace text in Python?
ProblemYou want to search for and replace a text pattern in a string.If we have a very simple literal patterns, using the str.replace() method is an optimal solution.Exampledef sample(): yield 'Is' yield 'USA' yield 'Colder' yield 'Than' yield 'Canada?' text = ' '.join(sample()) print(f"Output {text}")OutputIs USA Colder Than Canada?Let us first see how to search a text.# search for exact text print(f"Output {text == 'USA'}")OutputFalseWe can search for the text using the basic string methods, such as str.find(), str.endswith(), str.startswith().# text start with print(f"Output {text.startswith('Is')}")OutputTrue# text ends with print(f"Output {text.startswith('Is')}")OutputTrue# search text with find print(f"Output ...
Read MoreHow to Implement Priority Queue in Python?
Introduction...The queue module provides a first-in, first-out (FIFO), Last-in, First out (LIFO) data structure suitable for multi-threaded programming. Queues can be used to pass data or any wide range of information e.g. session details, paths, variables, .. between creator and consumer threads safely. Locking is generally handled for the caller.Note : This discussion assumes you already understand the general nature of a queue. If you do not, you may want to read some of the references before continuing.1. Let us implement a basic FIFO Queue.import queue fifo = queue.Queue() # put numbers into queue for i in range(5): fifo.put(i) ...
Read MoreHow to Find The Largest Or Smallest Items in Python?
This article is aimed at developers who want to find the largest or smallest items with Python. I will show a few methods touse and will conclude the best method for you.Method – 1: Slice approach on a ListIf you are simply trying to find the single smallest or largest item i.e N = 1, it is faster to use min() and max().Let us begin by generating some random integers.import random # Create a random list of integers random_list = random.sample(range(1, 10), 9) random_listOutput[2, 4, 5, 1, 7, 9, 6, 8, 3] FINDING THE SMALLEST & LARGEST ITEM (N=1) # ...
Read MoreHow to Identify Most Frequently Occurring Items in a Sequence with Python?
ProblemYou need to identify the most frequently occurring items in a sequence.SolutionWe can use counter to keep track of the items in a sequence.What is a Counter ?The “Counter” is a mapping that holds an integer count for each key. Updating an existing key adds to its count. This Objectis used for counting the instances of hashable objects or as a multiset.The “Counter” is one of your best friends when you are performing data analysis.This object has been present in Python for quite some time, and so for a lot of you, this will be a quick review.We will start ...
Read MoreHow to improve file reading performance in Python with MMAP function?
Introduction..MMAP abbreviated as memory mapping when mapped to a file uses the operating systems virtual memory to access the data on the file system directly, instead of accessing the data with the normal I/O functions. There by improving the I/O performance as it does not require either making a separate system call for each access or copying data between buffers.To a matter of fact anything in memory for instance a SQLlite database when created in-memeory has better performance compared to on disk.Memory-mapped files can be treated as mutable strings or file-like objects, depending on what you want to do.MMAP supports ...
Read MoreHow to read text files using LINECACHE in Python
Solution..The linecache module implements cache which holds the contents of files, parsed into separate lines, in memory. linecache module returns line/s by indexing into a list, and saves time over repeatedly reading the file and parsing lines to find the one desired.lincecache module is very useful when looking for multiple lines from the same file.Prepare test data. You can get this text by just using Google and searching for sample text.Lorem ipsum dolor sit amet, causae apeirian ea his, duo cu congue prodesset. Ut epicuri invenire duo, novum ridens eu has, in natum meliore noluisse sea. Has ei stet explicari. ...
Read MoreHow to compare files in Python
Problem.You need to compare files in Python.Solution..The filecmp module in python can be used to compare files and directories. 1.cmp(file1, file2[, shallow])filecmp Compares the files file1 and file2 and returns True if identical, False if not. By default, files that have identical attributes as returned by os.stat() are considered to be equal. If shallow is not provided (or is True), files that have the same stat signature are considered equal.cmpfiles(dir1, dir2, common[, shallow])Compares the contents of the files contained in the list common in the two directories dir1 and dir2. cmpfiles returns a tuple containing three lists - match, mismatch, ...
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