摘要： Introduction In daily data analysis, we often face table has date columns. In different data sources, the format of date can be very different. This w 阅读全文

摘要： Introduction In daily analysis we will face a simple chanllenge: how to add a summary row for our table? # A tibble: 5 × 2 cut avg_pri <ord> <dbl> 1 F 阅读全文

摘要： 1. Why do I care? In R, when we want to create a new column we often use mutate() function. A little complex situation is that this new column is base 阅读全文

摘要： 1. What is a bee swarm plot? Bee swarm plot is a categorical scatter plot. A normal scatter plot has problem when you come to compare groups of data s 阅读全文

摘要： 1. Introduction nullif() has two parameters. The first one, is a variable, and the second one is a real number. We want a result that when param1 equa 阅读全文

摘要： 1. Introduction In R language, we often use group_by() with summarise() to do summary. If we group_by() multiple columns, we will have a multi-index t 阅读全文

摘要： 1. Introduction If you are reading this article I suppose you use C. In C, we do not have dictionary or map or other key-value pair collection by defa 阅读全文

摘要： 1. Introduction In this article we will discuss over() function in SQL. over() is used in conjunction with other functions and mostly it means to scat 阅读全文

摘要： WARNING: This is only a test application for SQL learning. If you are in business production environment, you should not follow this article. 1. How t 阅读全文

摘要： 1. Introduction Different people may have different idea on "pivot data": If you are an Excel expert, you may think it as creating an excel pivot tabl 阅读全文