Different ways to count NAs over multiple columns

There are a number of ways in R to count NAs (missing values). A common use case is to count the NAs over multiple columns, ie., a whole dataframe. That’s basically the question “how many NAs are there in each column of my dataframe”? This post demonstrates some ways to answer this question. Way 1: using sapply A typical way (or classical way) in R to achieve some iteration is using apply and …