Just like cbind() has rbind(), colSums() has rowSums(). Your R workspace already contains the all_wars_matrix that you constructed in the previous exercise; type all_wars_matrix to have another look. Let's now calculate the total box office revenue for the entire saga.
total_revenue_vector. You can use the colSums() function.total_revenue_vector to have a look at the results.
# Construct matrix
load(url("http://s3.amazonaws.com/assets.datacamp.com/course/intro_to_r/all_wars_matrix.RData"))
# all_wars_matrix is available in your workspace
all_wars_matrix
# Total revenue for US and non-US
total_revenue_vector <-
# Print out total_revenue_vector
# all_wars_matrix is available in your workspace
all_wars_matrix
# Total revenue for US and non-US
total_revenue_vector <- colSums(all_wars_matrix)
# Print out total_revenue_vector
total_revenue_vector
msg = "Do not change the contents of `all_wars_matrix`; it was created for you in the workspace."
test_object("all_wars_matrix", eq_condition = "equal", undefined_msg = msg, incorrect_msg = msg)
test_function("colSums", "x", incorrect_msg = "Did you use the `colSums()` function on the all_wars_matrix?")
test_object("total_revenue_vector",
incorrect_msg = "Have you correctly assigned the result of `colSums(all_wars_matrix)` to `total_revenue_vector`?")
test_output_contains("total_revenue_vector", incorrect_msg = "Don't forget to print out `total_revenue_vector`!")
success_msg("Bellissimo! Head over to the next exercise to learn matrix subsetting.")
You should use the colSums() function with star_wars_matrix as the argument to find the total box office per region.