The %in% operator Answer Key

Author

Will Gammerdinger

Published

July 1, 2025

Exercise 1

Using the A and B vectors created above, evaluate each element in B to see if there is a match in A

# Return a boolean vector of elements in B that are in A
B %in% A

[1] FALSE FALSE FALSE FALSE  TRUE  TRUE

Subset the B vector to only return those values that are also in A.

# Return a boolean vector of elements in B that are in A and assign it to the object intersectionBA
intersectionBA <- B %in% A

# Subset the B vector by the elements returning TRUE in intersectionBA
B[intersectionBA]

[1] 1 5

Alternatively, you can use a nested approach:

# Identify the elements in B that are in A and subset the B vector by those elements
B[B %in% A]

[1] 1 5

---
title: "The %in% operator Answer Key"
author:
  - Will Gammerdinger
date: "2025-07-01"
---

```{r}
#| label: load_data
#| echo: false
# Set A and B vectors
A <- c(1,3,5,7,9,11)   # odd numbers
B <- c(2,4,6,8,1,5)  # add some odd numbers in 
```

# Exercise 1

1. Using the `A` and `B` vectors created above, evaluate each element in `B` to see if there is a match in `A`
    
```{r}
#| label: find_b_in_a
# Return a boolean vector of elements in B that are in A
B %in% A
```
2. Subset the `B` vector to only return those values that are also in `A`.
    
```{r}
#| label: subset_b_in_a
# Return a boolean vector of elements in B that are in A and assign it to the object intersectionBA
intersectionBA <- B %in% A

# Subset the B vector by the elements returning TRUE in intersectionBA
B[intersectionBA]
```

Alternatively, you can use a nested approach:

```{r}
#| label: nested_subset_b_in_a
# Identify the elements in B that are in A and subset the B vector by those elements
B[B %in% A]
```