Part 21 Filtering and mutating data frames
21.1 Learning Objectives
Here are the concepts we’ll be exploring in this lesson:
- Relational/comparison operators
- Logical operators
- dplyr functions:
- filter
- mutate
By the end of this lesson, you will be able to:
- Predict the output of R code containing the above operators.
- Explain the difference between
&/&&and|/||, and name a situation where one should be used over the other. - Subsetting and transforming data using filter and mutate
21.2 R Operators
Arithmetic operators allow us to carry out mathematical operations:
| Operator | Description |
|---|---|
| + | Add |
| - | Subtract |
| * | Multiply |
| / | Divide |
| ^ | Exponent |
| %/% | Integer division |
| %% | Modulus (remainder from integer division) |
Relational operators allow us to compare values:
| Operator | Description |
|---|---|
| < | Less than |
| > | Greater than |
| <= | Less than or equal to |
| >= | Greater than or equal to |
| == | Equal to |
| != | Not equal to |
- Arithmetic and relational operators work on vectors.
There is another very useful relational function, %in%:
c(1, 2, 3, 4, 5) %in% c(1, 2)Logical operators allow us to carry out boolean operations:
| Operator | Description |
|---|---|
| ! | Not |
| | | Or (element_wise) |
| & | And (element-wise) |
| || | Or |
| && | And |
- The difference between
|and||is that||evaluates only the first element of the two vectors, whereas|evaluates element-wise.
21.3 Demonstration
Continue along with the worksheet until Back to Guide Again.