Building on the if else foundation from the previous lesson, we will explore two efficient alternatives: the ifelse function and the case when block.

The ifelse function

When we created an if else block in the previous lesson, it spanned several lines due to the requirement of incorporating curly brackets after each conditional expression. However, if the actions within these expressions are quite straightforward, we can opt for a more condensed representation using the ifelse function, essentially boiling the block down to a single line.

Let's break down the structure of this function. The ifelse(condition, a, b) function encompasses three components: the condition parameter, which is an expression that will be evaluated and must result in a boolean value; the a parameter, which contains the code to be executed if the condition yields TRUE; and the b parameter, where the code to run when the condition is FALSE resides. To illustrate this concept further, we'll demonstrate how to condense the if else block from the 3rd code editor in the previous lesson into a streamlined ifelse statement.

One difference here is that the ifelse function will return the value of the expression that is executed, whereas the if else block will not return anything. This means that we can assign the result of the ifelse function to a variable, as we did with y in the example above, so that we may print it out.

Case when

In the previous lesson, we explored the use of if, else if, else conditions to examine multiple scenarios. While it is entirely possible to add more else if statements to encompass additional conditions, doing so can lead to extensive, hard-to-maintain code. A more efficient and tidy approach is to utilize the case_when function, which enables us to inspect a series of conditions and allot a value corresponding to the true condition. Feel free to change the value of a to see the different outputs.

Now let's see the same code but this time using multiple if, else if, else conditions. This will have the same result, however as we can see the code is much more verbose.