# --3-Matrices \#1-What's a matrix? ```r #Construct a matrix with 3 rows containing the numbers 1 up to 9, # filled row-wise. matrix(1:9,byrow=TRUE,nrow=3) ``` \#2-Analyzing matrices ```r #Use c(new_hope, empire_strikes, return_jedi) to combine- #the three vectors into one vector. Call this vector box_office. #Construct a matrix with 3 rows, where each row represents a movie. #Use the matrix() function to this. #The first argument is the vector box_office, containing #all box office figures. #Next, you'll have to specify nrow = 3 and byrow = TRUE. #Name the resulting matrix star_wars_matrix. # Box office Star Wars (in millions!) new_hope <-c( 460.998 , 314.4 ) empire_strikes <- c(290.475, 247.900) return_jedi <- c(309.306, 165.8) # Create box_office box_office <-c(new_hope,empire_strikes,return_jedi) # Construct star_wars_matrix star_wars_matrix <- matrix(box_office,byrow=TRUE,nrow=3) star_wars_matrix ``` \#3-Naming a matrix ```r #Use colnames() to name the columns of star_wars_matrix with #the region vector. #Use rownames() to name the rows of star_wars_matrix with the #titles vector. #Print out star_wars_matrix to see the result of your work. # Box office Star Wars (in millions!) new_hope <- c(460.998, 314.4) empire_strikes <- c(290.475, 247.900) return_jedi <- c(309.306, 165.8) # Construct matrix star_wars_matrix <- matrix(c(new_hope, empire_strikes, return_jedi), nrow = 3, byrow = TRUE) # Vectors region and titles, used for naming region <- c("US", "non-US") titles <- c("A New Hope", "The Empire Strikes Back", "Return of the Jedi") # Name the columns with region colnames(star_wars_matrix)<-region # Name the rows with titles rownames(star_wars_matrix)<-titles # Print out star_wars_matrix star_wars_matrix ``` \#4-Calculating the worldwide box office ```r #Calculate the worldwide box office figures for #the three movies and put these in the vector named worldwide_vector. # Construct star_wars_matrix box_office <-c(460.998, 314.4, 290.475, 247.900, 309.306, 165.8) star_wars_matrix <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi"), c("US", "non-US"))) star_wars_matrix # Calculate worldwide box office figures worldwide_vector <- rowSums(star_wars_matrix) worldwide_vector ``` \#5-Adding a column for the Worldwide box office ```r #Add worldwide_vector as a new column to the star_wars_matrix and #assign the result to all_wars_matrix. #Use the cbind() function. # Construct star_wars_matrix box_office <- c(460.998, 314.4, 290.475, 247.900, 309.306, 165.8) star_wars_matrix <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi"), c("US", "non-US"))) star_wars_matrix # The worldwide box office figures worldwide_vector <- rowSums(star_wars_matrix) worldwide_vector # Bind the new variable worldwide_vector as a column to #star_wars_matrix all_wars_matrix <- cbind(star_wars_matrix,worldwide_vector) all_wars_matrix ``` \#6-Adding a row ```r #Use rbind() to paste together star_wars_matrix and star_wars_matrix2, #in this order. #Assign the resulting matrix to all_wars_matrix. # Construct star_wars_matrix1 box_office <- c(460.998, 314.4, 290.475, 247.900, 309.306, 165.8) star_wars_matrix <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi") , c("US", "non-US"))) star_wars_matrix # Construct star_wars_matrix2 box_office2 <- c( 474.5, 552.5, 552.5, 338.7, 380.3, 468.5) star_wars_matrix2 <- matrix(box_office2, nrow = 3, byrow = TRUE, dimnames = list(c("The Phantom Menace", "Attack of the Clones", "Revenge of the Sith") , c("US", "non-US"))) star_wars_matrix2 # star_wars_matrix and star_wars_matrix2 are available in #your workspace star_wars_matrix star_wars_matrix2 # Combine both Star Wars trilogies in one matrix all_wars_matrix <- rbind(star_wars_matrix,star_wars_matrix2) all_wars_matrix ``` \#7-The total box office revenue for the entire saga ```r # Construct star_wars_matrix1 box_office <- c(460.998, 314.4, 290.475, 247.900, 309.306, 165.8) star_wars_matrix <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi") , c("US", "non-US"))) star_wars_matrix # Construct star_wars_matrix2 box_office2 <- c( 474.5, 552.5, 552.5, 338.7, 380.3, 468.5) star_wars_matrix2 <- matrix(box_office2, nrow = 3, byrow = TRUE, dimnames = list(c("The Phantom Menace", "Attack of the Clones", "Revenge of the Sith") , c("US", "non-US"))) star_wars_matrix2 # star_wars_matrix and star_wars_matrix2 are available in #your workspace star_wars_matrix star_wars_matrix2 # Combine both Star Wars trilogies in one matrix all_wars_matrix <- rbind(star_wars_matrix,star_wars_matrix2) 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 ``` \#8-Selection of matrix elements ```r # Construct star_wars_matrix1 box_office <- c(460.998, 314.4, 290.475, 247.900, 309.306, 165.8) star_wars_matrix <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi") , c("US", "non-US"))) star_wars_matrix # Construct star_wars_matrix2 box_office2 <- c( 474.5, 552.5, 552.5, 338.7, 380.3, 468.5) star_wars_matrix2 <- matrix(box_office2, nrow = 3, byrow = TRUE, dimnames = list(c("The Phantom Menace", "Attack of the Clones", "Revenge of the Sith") , c("US", "non-US"))) star_wars_matrix2 # star_wars_matrix and star_wars_matrix2 are available in #your workspace star_wars_matrix star_wars_matrix2 # Combine both Star Wars trilogies in one matrix all_wars_matrix <- rbind(star_wars_matrix,star_wars_matrix2) all_wars_matrix # Select the non-US revenue for all movies non_us_all <- all_wars_matrix[,2] # Average non-US revenue mean(non_us_all) # Select the non-US revenue for first two movies non_us_some <- all_wars_matrix[1:2,2] # Average non-US revenue for first two movies mean(non_us_some) ``` \#9-A little arithmetic with matrices ```r # Construct star_wars_matrix1 box_office <- c(460.998, 314.4, 290.475, 247.900, 309.306, 165.8) star_wars_matrix <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi") , c("US", "non-US"))) star_wars_matrix # Construct star_wars_matrix2 box_office2 <- c( 474.5, 552.5, 552.5, 338.7, 380.3, 468.5) star_wars_matrix2 <- matrix(box_office2, nrow = 3, byrow = TRUE, dimnames = list(c("The Phantom Menace", "Attack of the Clones", "Revenge of the Sith") , c("US", "non-US"))) star_wars_matrix2 # star_wars_matrix and star_wars_matrix2 are available in your workspace star_wars_matrix star_wars_matrix2 # Combine both Star Wars trilogies in one matrix all_wars_matrix <- rbind(star_wars_matrix,star_wars_matrix2) all_wars_matrix # Estimate the visitors visitors <- all_wars_matrix/5 # Print the estimate to the console visitors ``` \#10- A little arithmetic with matrices (2) ```r # Construct star_wars_matrix1 box_office <- c(460.998, 314.4, 290.475, 247.900, 309.306, 165.8) star_wars_matrix <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi") , c("US", "non-US"))) star_wars_matrix # Construct star_wars_matrix2 box_office2 <- c( 474.5, 552.5, 552.5, 338.7, 380.3, 468.5) star_wars_matrix2 <- matrix(box_office2, nrow = 3, byrow = TRUE, dimnames = list(c("The Phantom Menace", "Attack of the Clones", "Revenge of the Sith") , c("US", "non-US"))) star_wars_matrix2 # star_wars_matrix and star_wars_matrix2 are available in #your workspace star_wars_matrix star_wars_matrix2 # Combine both Star Wars trilogies in one matrix all_wars_matrix <- rbind(star_wars_matrix,star_wars_matrix2) all_wars_matrix # create ticket_prices_matrix box_office <- c(5,5, 6,6, 7,7) ticket_prices_matrix1 <- matrix(box_office, nrow = 3, byrow = TRUE, dimnames = list(c("A New Hope", "The Empire Strikes Back", "Return of the Jedi"), c("US", "non-US"))) # Construct ticket_prices_matrix2 box_office2 <- c(4,4, 4.5,4.5, 4.9,4.9) ticket_prices_matrix2<- matrix(box_office2, nrow = 3, byrow = TRUE, dimnames = list(c("The Phantom Menace", "Attack of the Clones", "Revenge of the Sith") , c("US", "non-US"))) ticket_prices_matrix<-rbind(ticket_prices_matrix1,ticket_prices_matrix2) # Estimated number of visitors visitors <- all_wars_matrix/ticket_prices_matrix # US visitors us_visitors <- visitors[,1] # Average number of US visitors mean(us_visitors) ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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