1. Relational Operators
Hi, and welcome to the first video of the Intermediate R course. My name is Filip, I'm a content creator at DataCamp and I will help you master a bunch of new concepts in the R programming language. Next stop on our trip through the wonderful world of R: relational operators!
2. Equality ==
Relational operators, or comparators, are operators which help us see how one R object relates to another. For example, you can check whether two objects are equal. You can do this by using a double equals sign. We can for example see if the logical value TRUE equals the logical value TRUE. Let's try it out in the console: we type TRUE equals equals TRUE. The result of this query is a logical value, in this case TRUE, because TRUE equals TRUE. On the contrary, TRUE == FALSE will give us FALSE. Makes sense, right?
Apart from logical variables, we can also check the equality of other types. We can also compare strings and numbers.
3. Inequality !=
The opposite of the equality operator is the inequality operator, written as an exclamation mark followed by an equals sign. This sentence would read as: "hello" is not equal to "goodbye". Because this statement is correct, R will output TRUE. Naturally, the inequality operator can also be used for numerics, logicals, and of course other R objects as well. See how every time, the result of the equality operator is opposite for the inequality operator.
4. < and >
Of course, there are also cases where you need more than simply equality and inequality operators. What about checking if an R object is 'less than' or 'greater than' another R object? This will not come as a surprise: you can use the less-than and greater-than sign for this. In the case of numerical values, here is a straightforward example: 3 less than 5 will evaluate to TRUE, while 3 greater than 5 will evaluate to FALSE.
For numerics this makes sense, but how would this work for character strings and logical values? Is "Hello" greater than "Goodbye"? Let's find out! Apparently "Hello" greater than "Goodbye" evaluates to TRUE, but why so? It's because R uses the alphabet to sort character strings. Since "H" comes after "G" in the alphabet, "Hello" is considered greater than "Goodbye".
How about logical values? Is TRUE less than FALSE? The following query gives us the answer. It appears not; it evaluates to FALSE. That's because under the hood, TRUE corresponds to 1 and FALSE corresponds to 0. And of course 1 is not less than 0, hence the FALSE result.
5. <= and >=
You can also check to see if one R object is greater than or equal to (or less than or equal to) another R object. To do this, you can use the less than sign, or the greater than sign, together with the equals sign. So 5 greater than or equal to 3 as well as 3 greater than or equal to 3 will evaluate to TRUE.
6. Relational Operators & Vectors
You already knew that R is pretty good with vectors. How about R's comparators, can they also handle vectors? Suppose you have recorded the daily number of views your LinkedIn profile had the previous week and stored them in a vector, linkedin. If we want to find out on which days the number of views exceeded 10, we can directly use the greater than sign. For the first, third, sixth and seventh element in the vector, the number of views is greater than 10, so for these elements the result will be TRUE.
7. Relational Operators & Vectors
You can also compare vectors to vectors; suppose you also recorded the number of views your Facebook profile had the previous week and saved them in another vector, facebook. When are the number of Facebook views less than or equal to the number of LinkedIn views? The following expression shows us how to calculate this.
Does it make sense? In this case, the comparison is done for every element of the vector, one by one. For example, in the third day, the number of Facebook views is 5 and the number of LinkedIn views is 13. The comparison evaluates to TRUE, as 5 is smaller than or equal to 13.
8. Let's practice!
Just as for vectors, R also knows how to compare other data structures, such as matrices and lists. Head over the interactive exercises and add Relational Operators to your ever growing R skillset!