Chris
NumPy is a popular Python library for data science focusing on arrays, vectors, and matrices. This article introduces the np.average() function from the NumPy library. When applied to a 1D array, this function returns the average of the array values. When applied to a 2D array, NumPy simply flattens the array. The result is the … Read more
Python’s built-in round() function takes two input arguments: a number and an optional precision in decimal digits. It rounds the number to the given precision and returns the result. The return value has the same type as the input number—or integer if the precision argument is omitted. Per default, the precision is set to 0 … Read more
NumPy is a popular Python library for data science for array, vector, and matrix computations. This puzzle introduces basic indexing of elements in NumPy arrays. Problem Formulation: How to index elements in NumPy arrays? Indexing 1D Arrays with Positive Indices The most simple use of indexing is with the square bracket notation and positive integers: … Read more
Problem Formulation: How to calculate the standard deviation in NumPy? Differentiations: There are many different variants of this problem: Calculate the standard deviation of a 1D array Calculate the standard deviation of a 2D array Calculate the standard deviation of a 3D array Then you can also calculate the standard deviation along an axis: Calculate … Read more
Python’s built-in issubclass(X, Y) function takes a class X and a class Y and returns True if the X is an instance of Y and otherwise False. The argument Y can also be a tuple in which case it checks whether X is a subclass of any class in the tuple—such as in issubclass(X, (class_1, … Read more
Did you check the news today, or receive an email newsletter from a company? Both modes of communication follow the publish-subscribe communication pattern. This article will show you how to implement your own PubSub system in Python using the flexible PyPubSub library. If you already know about the PubSub concept, feel free to move to … Read more
Python’s built-in reversed(sequence) function returns a reverse iterator over the values of the given sequence such as a list, a tuple, or a string. Usage Learn by example! Here are some examples of how to use the reversed() built-in function. The most basic use is on a Python list: You can see that the return … Read more
Problem Formulation: How to perform an HTTP get call in Python? Solution: Use Python’s requests library. This is semantically equivalent to issuing an HTTP get call: http://example.com?param_1=value_1¶m_2=value_2 In fact, you can obtain this exact URL by using the r.url attribute on the request object: You can find the text response by using the r.text attribute … Read more
Python’s built-in isinstance(object, class) function takes an object and a class as input arguments. It returns True if the object is an instance of the class. Otherwise, it returns False. Instead of a class, you can also pass a tuple of classes to check if the object is an instance of any of the classes … Read more
Problem Formulation: Given a Python object. How to check if the given Python object is of type list? Example: Given a dictionary for which you don’t know the values associated to the keys. For example, suppose you have entry dict[key] for which you don’t know the type. How to check if it’s a list? Given: … Read more
Problem Formulation: Given a byte string that contains new-line characters ‘\n’. How to split the byte string into a list of lines? Example: You want to transform the byte string b’your\nbyte\nstring’ into the list of byte strings [b’your’, b’byte’, b’string’] using b’\n’ as a newline separator. Given: b’your\nbyte\nstring’ Goal: [b’your’, b’byte’, b’string’] Solution: To split … Read more
Python’s built-in frozenset() function creates and returns a new frozenset object. A frozenset is an immutable set—so you cannot change the frozenset after creation and set methods such as add() or remove() don’t work on the frozenset. Without an argument, frozenset() returns an empty frozenset. With the optional argument, frozenset(iter) initializes the new frozenset with … Read more