The Mysterious Case of auto_test_package Writing tests for R packages can be a daunting task, especially when it comes to setting up and running automated testing. In this article, we will delve into the world of testthat and auto_test_package to understand why auto_test_package is throwing errors even though test_package passes. Installing Required Packages Before we begin, let’s make sure we have the necessary packages installed. Both testthat and devtools are required for this tutorial.

MySQL Generated Column Multiplier Variable Introduction In this article, we’ll explore a common MySQL query pattern that generates a column multiplier variable based on another variable. We’ll dive into the technical details of how to achieve this using stored functions and prepared statements. Understanding Stored Functions in MySQL In MySQL, stored functions are blocks of code that can be executed repeatedly without having to rewrite the entire code every time. These functions are defined before they’re used and can be used in queries just like regular columns or variables.

Creating a New DataFrame by Slicing Rows from an Existing DataFrame =========================================================== In this article, we will explore how to create a new DataFrame in Python using the pandas library by slicing rows from an existing DataFrame. This technique allows you to store off rows that throw exceptions into a new DataFrame. Understanding DataFrames and Row Slicing A DataFrame is a two-dimensional data structure with columns of potentially different types. It’s similar to an Excel spreadsheet or a table in a relational database.

SQL (Postgres) Performance Optimization: Understanding JOIN in EXISTS Queries As a developer, optimizing database queries is crucial to ensure efficient performance and scalability. In this article, we’ll delve into the world of SQL and explore how to improve the performance of complex queries, specifically those involving JOINs and EXISTS clauses. The Problem: Bad Performance with JOIN in EXISTS Suppose you have three tables: person, task, and a junction table person_task. There’s a many-to-many relationship between these tables, making it essential to use a join.

Understanding UIActionSheets in iOS Development Introduction to ActionSheets In iOS development, an UIActionSheet is a modal window that provides a way for the user to select from a set of actions. It’s commonly used when a button or other control needs to present a list of options to the user. However, one common issue developers face when working with action sheets is ensuring they are displayed correctly in different orientations and positions on the screen.

Understanding the Problem and the Solution Using cor.test() In this article, we will delve into the world of correlation analysis in R, specifically focusing on how to handle missing values (NA) when calculating Spearman correlations between two columns using the cor.test() function. Background and Context The Spearman correlation coefficient is a non-parametric measure of correlation that is resistant to outliers and non-normality. It measures the monotonic relationship between two variables, where an increase in one variable corresponds to an increase (or decrease) in the other variable.

Understanding iOS App Lifecycle and Identifying Home Button Presses As a developer working on iOS applications, understanding the app lifecycle is crucial for creating smooth and responsive user experiences. One often overlooked aspect of the app lifecycle is identifying when the home button is pressed and determining whether it was an internal or external event that triggered the press. What is the App Lifecycle? The app lifecycle refers to the series of events that occur when an iOS application is launched, runs in the background, and terminated.

Understanding UIButton Scaling and Gestures in iOS Development As a developer, creating intuitive user interfaces is crucial for delivering a seamless user experience. In this article, we’ll explore how to increase the size of a UIButton temporarily on touch and discuss whether using gestures is the best approach. Background: UIButton and Touch Events A UIButton is a basic UI element in iOS development that allows users to interact with your app by tapping it.

How to ignore NAs in certain rows to calculate a group-level 5-year weighted average in R In this article, we will discuss how to handle missing values (NA) when calculating weighted averages for specific groups. We will use the data.table package and explore ways to exclude rows with NA values from the calculation. Background: Understanding Data Manipulation in R Before diving into the solution, it’s essential to understand some fundamental concepts in R data manipulation.

Using “count” Function in a Loop in R ===================================================== The count function in R is used to count the frequency of each unique value in a specified column. However, when attempting to use this function within a loop, one may encounter issues with the variable names and data structure. In this article, we will explore the correct way to perform a count using the count function in R, focusing on avoiding loops and instead leveraging the power of tidyverse functions.