Guide to String Interning in Python

Introduction One of the first things you encounter while learning the basics of programming is the concept of strings. Similar to various programming languages, Python strings are arrays of bytes representing Unicode characters – an array or sequence of characters. Python, unlike many programming languages, doesn’t have a distinct character datatype, and characters are considered strings of length 1. You can define a string using single or double quotation marks, for example, a = “Hello World” or a = ‘Hello […]

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Python: Check if Variable is a Number

Introduction In this article, we’ll be going through a few examples of how to check if a variable is a number in Python. Python is dynamically typed. There is no need to declare a variable type, while instantiating it – the interpreter infers the type at runtime: variable = 4 another_variable = ‘hello’ Additionally, a variable can be reassigned to a new type at any given time: # Assign a numeric value variable = 4 # Reassign a string value […]

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Python: Check if File or Directory is Empty

Introduction Python has a set of built-in library objects and functions to help us with this task. In this tutorial, we’ll learn how to check if a file or directory is empty in Python. Distinguish Between a File and a Directory When we’d like to check if a path is empty or not, we’ll want to know if it’s a file or directory since this affects the approach we’ll want to use. Let’s say we have two placeholder variables dirpath […]

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Kernel Density Estimation in Python Using Scikit-Learn

Introduction This article is an introduction to kernel density estimation using Python’s machine learning library scikit-learn. Kernel density estimation (KDE) is a non-parametric method for estimating the probability density function of a given random variable. It is also referred to by its traditional name, the Parzen-Rosenblatt Window method, after its discoverers. Given a sample of independent, identically distributed (i.i.d) observations ((x_1,x_2,ldots,x_n)) of a random variable from an unknown source distribution, the kernel density estimate, is given by: $$p(x) = frac{1}{nh} […]

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Replace Occurrences of a Substring in String with Python

Introduction Replacing all or n occurrences of a substring in a given string is a fairly common problem of string manipulation and text processing in general. Luckily, most of these tasks are made easy in Python by its vast array of built-in functions, including this one. Let’s say, we have a string that contains the following sentence: The brown-eyed man drives a brown car. Our goal is to replace the word “brown” with the word “blue”: The blue-eyed man drives […]

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Facial Detection in Python with OpenCV

Introduction Facial detection is a powerful and common use-case of Machine Learning. It can be used to automatize manual tasks such as school attendance and law enforcement. In the other hand, it can be used for biometric authorization. In this article, we’ll perform facial detection in Python, using OpenCV. OpenCV OpenCV is one of the most popular computer vision libraries. It was written in C and C++ and also provides support for Python, besides Java and MATLAB. While it’s not […]

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Padding Strings in Python

Introduction String padding refers to adding, usually, non-informative characters to a string to one or both ends of it. This is most often done for output formatting and alignment purposes, but it can have useful practical applications. A frequent use case for padding strings is outputting table-like information in a table-like fashion. You can do this in a variety of ways, including using Pandas to convert your data to an actual table. This way, Python would handle the output formatting […]

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Serving Static Files in Python With Django, AWS S3 and WhiteNoise

Introduction Websites generally need additional files such as images, CSS, and JavaScript files that are necessary to render complete web pages in a browser. In small projects, we can work our way around by providing absolute paths to our resources or by writing inline CSS and JavaScript functions in the HTML files. This is not only against the best coding practices but it also gets tricky when we are handling bigger projects, especially with multiple applications. In Django, the files […]

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Change Figure Size in Matplotlib

Introduction Matplotlib is one of the most widely used data visualization libraries in Python. Much of Matplotlib’s popularity comes from its customization options – you can tweak just about any element from its hierarchy of objects. In this tutorial, we’ll take a look at how to change a figure size in Matplotlib. Creating a Plot Let’s first create a simple plot in a figure: import matplotlib.pyplot as plt import numpy as np x = np.arange(0, 10, 0.1) y = np.sin(x) […]

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Deep Learning in Keras – Building a Deep Learning Model

Introduction Deep learning is one of the most interesting and promising areas of artificial intelligence (AI) and machine learning currently. With great advances in technology and algorithms in recent years, deep learning has opened the door to a new era of AI applications. In many of these applications, deep learning algorithms performed equal to human experts and sometimes surpassed them. Python has become the go-to language for Machine Learning and many of the most popular and powerful deep learning libraries […]

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