![Numpy Weighted Average np.average(array, axis=0, weights=[0.1,0.1,0.8])](https://blog.finxter.com/wp-content/uploads/2018/08/Numpy-Weighted-Average.png)
Problem Formulation: How to calculate the weighted average of the elements in a NumPy array? Definition weighted average: Each array element has an associated weight. The weighted average is the sum of all array elements, properly weighted, divided by the sum of all weights. Here’s the problem exemplified: Quick solution: Before we discuss the solution … Read more
Python’s built-in repr(obj) function returns the standard string representation of the provided object. This often includes the type and memory address of the object—for lack of further information. For example, the returned string representation may be ‘<main.Car object at 0x000001F66D11DBE0>’ for a custom object of type Car. The function internally calls the method obj.__repr__() which … Read more
Python’s built-in str(x) function converts the object x to a string using the x.__str__() method or, if non-existent, the repr(x) built-in function to obtain the string conversion. Syntax str() Syntax: str(object) # –> Most common case: convert an object to a string str(object=b”, encoding=’utf-8′, errors=’strict’) # –> Not so common case: Converts a bytes or … Read more
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
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
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
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: Given a dictionary in Python; how to switch Keys and Values? Method 1: Using a for loop Method 2: Using the zip function Method 3: Using the map and reverse functions Method 4: Using a dictionary comprehension Summary: Use one of the following methods to switch between the keys and values in a dictionary with unique values. … 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
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