Create List of Vectors Using Rcpp Package in R (Example)

In the following, we show you how to do create a list of vectors with the Rcpp package in R.

The structure is as follows:

1) Create Example Vectors

2) Example 1: Unnamed List of Vectors in Rcpp

3) Example 2: Named List of Vectors in Rcpp

4) Video & Further Resources

5) Subscribe to the Statistics Globe Newsletter

6) Thank you!

Let’s list some vectors!

Create Example Vectors

First, we need to load the Rcpp package to be able to use C++ code in R.

if (!require('Rcpp', quietly = TRUE)) { install.packages('Rcpp') } 
library('Rcpp') # Load package 'Rcpp'

We create three example vectors x, y, and z, which we want to combine to a list.

x <- 1:5                    # numeric
y <- LETTERS[1:10]          # string
z <- c(TRUE, FALSE, FALSE)  # logical

You probably know from your experience with R that we can create unnamed lists and named lists. We show you an example of an unnamed and a named list of vectors x, y, and z in R below. With the example, you can also see that a list can take elements of different forms, types, and sizes.

list(x, y, z) # creates a list without specific names for the list elements
# [[1]]
# [1] 1 2 3 4 5
# 
# [[2]]
# [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J"
# 
# [[3]]
# [1]  TRUE FALSE FALSE
 
list("a" = x, "b" = y, "c" = z) # creates a list where we specifically name the elements
# $a
# [1] 1 2 3 4 5
# 
# $b
# [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J"
# 
# $c
# [1]  TRUE FALSE FALSE

Example 1: Unnamed List of Vectors in Rcpp

Like we did in R before, we can create an unnamed list of the three vectors in Rcpp with the function below.

cppFunction(' 
Rcpp::List f_vec_list( Rcpp::NumericVector x, 
                       Rcpp::StringVector  y, 
                       Rcpp::LogicalVector z) { 
 
   Rcpp::List res = Rcpp::List::create(x, y, z);
   return res;
}
')

f_vec_list(x, y, z)
# [[1]]
# [1] 1 2 3 4 5
# 
# [[2]]
# [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J"
# 
# [[3]]
# [1]  TRUE FALSE FALSE

Example 2: Named List of Vectors in Rcpp

Alternatively, we can also create a Rcpp list where we explicitly name the list elements “a”, “b”, and “c”, as shown in the function below.

cppFunction(' 
Rcpp::List f_vec_named_list( Rcpp::NumericVector x, 
                       Rcpp::StringVector  y, 
                       Rcpp::LogicalVector z) { 
 
   Rcpp::List res = Rcpp::List::create(Rcpp::Named("a") = x,
                          Rcpp::Named("b") = y,
                          Rcpp::Named("c") = z);
   return res;
}
')

f_vec_named_list(x, y, z)
# $a
# [1] 1 2 3 4 5
# 
# $b
# [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J"
# 
# $c
# [1]  TRUE FALSE FALSE

Video & Further Resources

For more information on Rcpp, we recommend you to take a look at the official Rcpp homepage here. Furthermore, on the CRAN page of Rcpp, which you can find here, you can find some useful additional references.

On https://statisticsglobe.com/, we have many more blog posts which you might want to look at:

We showed you how to create a list of vectors in Rcpp. If you have questions or comments, get in contact with us using the comment section below.

Anna-Lena Wölwer Survey Statistician & R Programmer

This page was created in collaboration with Anna-Lena Wölwer. Have a look at Anna-Lena’s author page to get further information about her academic background and the other articles she has written for Statistics Globe.