How to count TRUE values in a logical vector

📝 How to Count TRUE Values in a Logical Vector in R

Are you tired of struggling to count the number of TRUE values in a logical vector in R? Look no further! In this blog post, we will explore common issues, provide easy solutions, and reveal a more efficient approach to solve this problem. 🚀

The Problem

Imagine you have a logical vector z with 1000 elements, consisting of TRUE and FALSE values. Your task is to count the number of TRUE values in this vector.

The sample code presented in the context offers two possible solutions:

z <- sample(c(TRUE, FALSE), 1000, rep = TRUE)
sum(z)                 # Solution 1
table(z)["TRUE"]       # Solution 2

Solution 1: Using sum()

The first solution suggests using the sum() function to calculate the sum of TRUE values in the vector. By summing logical values, TRUE is converted to 1 and FALSE is converted to 0. Running sum(z) on our vector yields the desired result:

sum(z)
# [1] 498

Solution 2: Using table()

The second solution proposes using the table() function to build a frequency table of the vector values and then extracting the count for the TRUE value. Although it works, this solution involves additional steps and may seem less intuitive:

table(z)["TRUE"]
# TRUE 
#  498

A Better Solution: Using sum() with Boolean Conditions

While the aforementioned solutions are valid, there is an even better and more idiomatic way to solve this problem. We can directly use sum() in conjunction with a Boolean condition.

sum(z == TRUE)

By comparing each element of the vector z to TRUE, we obtain a vector of TRUE and FALSE values. Using sum() on this resulting vector gives us the desired count. This method eliminates the need for unnecessary conversions and additional steps.

💡 Quick Recap

• Solution 1: Use sum(z) to sum the logical values of TRUE and FALSE.

• Solution 2: Use table(z)["TRUE"] to build a frequency table and extract the count for the TRUE value.

🚀 Better Solution: Use sum(z == TRUE) with a Boolean condition for a more efficient and idiomatic approach.

Your Turn: Which Solution Do You Prefer?

Now that you've learned multiple solutions to count TRUE values in a logical vector, it's time to choose your favorite. Which solution do you find most intuitive and efficient? Or do you have another alternative you'd like to share?

Leave a comment below and let us know your preferred solution or any other insights you have on solving this problem! 💬

Remember to share this blog post with your fellow R users who might find it helpful! 📢

Happy coding! 😄