What is a Recommendation System? If you use Netflix or Amazon you have already seen the results of recommendation systems – movie or item recommendations that fit your taste or needs. So, at its core a recommendation system is a statistical algorithm that computes similarities based on previous choices or features and recommends users which … Read more
Python provides fantastic string formatting options, but what if you need greater control over how values are presented? That’s where format specifiers come in. This article starts with a brief overview of the different string formatting approaches. We’ll then dive straight into some examples to whet your appetite for using Python’s Format Specification Mini-Language in … Read more
To join a list of DataFrames, say dfs, use the pandas.concat(dfs) function that merges an arbitrary number of DataFrames to a single one. When browsing StackOverflow, I recently stumbled upon the following interesting problem. By thinking about solutions to those small data science problems, you can improve your data science skills, so let’s dive into … Read more
Python’s Tilde ~n operator is the bitwise negation operator: it takes the number n as binary number and “flips” all bits 0 to 1 and 1 to 0 to obtain the complement binary number. For example, the tilde operation ~1 becomes 0 and ~0 becomes 1 and ~101 becomes 010. Read all about the Tilde … Read more
This tutorial shows you how to group the inner lists of a Python list of lists by common element. There are three basic methods: Group the inner lists together by common element. Group the inner lists together by common element AND aggregating them (e.g. averaging). Group the inner lists together by common element AND aggregating … Read more
Short answer: To print a list of lists in Python without brackets and aligned columns, use the ”.join() function and a generator expression to fill each string with enough whitespaces so that the columns align: I’ll explain this code (and simpler variants) in the following video: As an exercise, you can also try it yourself … Read more
Pandas is an open-source Python library that is powerful and flexible for data analysis. If there is something you want to do with data, the chances are it will be possible in pandas. There are a vast number of possibilities within pandas, but most users find themselves using the same methods time after time. In this … Read more
Problem: You’re given a list of lists. Your goal is to convert it into a Pandas Dataframe. Example: Say, you want to compare salary data of different companies and job descriptions. You’ve obtained the following salary data set as a list of list: How can you convert this into a Pandas Dataframe? DataFrame() Solution: The … Read more
Want to calculate the standard deviation of a column in your Pandas DataFrame? In case you’ve attended your last statistics course a few years ago, let’s quickly recap the definition of variance: it’s the average squared deviation of the list elements from the average value. You can do this by using the pd.std() function that … Read more
This article shows you how to calculate the variance of a given list of numerical inputs in Python. In case you’ve attended your last statistics course a few years ago, let’s quickly recap the definition of variance: it’s the average squared deviation of the list elements from the average value. So, how to calculate the … Read more