# --5-Data frames \#1-What's a data frame? ```r #Click 'Submit Answer'. #The data from the built-in example data frame mtcars #will be printed to the console. datasets::mtcars # Print out built-in R data frame mtcars ``` \#2-Quick, have a look at your data set ```r # Call head() on mtcars head(mtcars) ``` \#3-Have a look at the structure ```r # Investigate the structure of mtcars str(mtcars) class(mtcars) attributes(mtcars) ``` \#4-Creating a data frame ```r #Use the function data.frame() to construct a data frame. #Pass the vectors name, type, diameter, rotation and rings #as arguments to data.frame(), in this order. # Definition of vectors name <- c("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune") type <- c("Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Gas giant", "Gas giant", "Gas giant", "Gas giant") diameter <- c(0.382, 0.949, 1, 0.532, 11.209, 9.449, 4.007, 3.883) rotation <- c(58.64, -243.02, 1, 1.03, 0.41, 0.43, -0.72, 0.67) rings <- c(FALSE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE) # Create a data frame from the vectors planets_df <-data.frame(name,type,diameter,rotation,rings) planets_df ``` \#5-Creating a data frame (2) ```r # Use str() to investigate the structure of the new planets_df variable. # Check the structure of planets_df in no #4-Creating a data frame str(planets_df) ``` \#6-Selection of data frame elements ```r #From planets_df, select the diameter of Mercury: #this is the value at the first row and the third column. #Simply print out the result. # Definition of vectors name <- c("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune") type <- c("Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Gas giant", "Gas giant", "Gas giant", "Gas giant") diameter <- c(0.382, 0.949, 1, 0.532, 11.209, 9.449, 4.007, 3.883) rotation <- c(58.64, -243.02, 1, 1.03, 0.41, 0.43, -0.72, 0.67) rings <- c(FALSE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE) # Create a data frame from the vectors planets_df <-data.frame(name,type,diameter,rotation,rings) planets_df # Print out diameter of Mercury (row 1, column 3) planets_df[1,3] # Print out data for Mars (entire fourth row) planets_df[4,] ``` \#7-Selection of data frame elements (2) ```r #Select and print out the first 5 values in the "diameter" #column of planets_df. # Definition of vectors name <- c("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune") type <- c("Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Gas giant", "Gas giant", "Gas giant", "Gas giant") diameter <- c(0.382, 0.949, 1, 0.532, 11.209, 9.449, 4.007, 3.883) rotation <- c(58.64, -243.02, 1, 1.03, 0.41, 0.43, -0.72, 0.67) rings <- c(FALSE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE) # Create a data frame from the vectors planets_df <-data.frame(name,type,diameter,rotation,rings) planets_df # Select first 5 values of diameter column planets_df[1:5,"diameter"] ``` \#8-Only planets with rings ```r #Use the $ sign to select the rings variable from planets_df. #Store the vector that results as rings_vector. #Print out rings_vector to see if you got it right. # Definition of vectors name <- c("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune") type <- c("Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Gas giant", "Gas giant", "Gas giant", "Gas giant") diameter <- c(0.382, 0.949, 1, 0.532, 11.209, 9.449, 4.007, 3.883) rotation <- c(58.64, -243.02, 1, 1.03, 0.41, 0.43, -0.72, 0.67) rings <- c(FALSE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE) # Create a data frame from the vectors planets_df <-data.frame(name,type,diameter,rotation,rings) planets_df # Select the rings variable from planets_df rings_vector <- planets_df$rings # Print out rings_vector rings_vector ``` \#9-Only planets with rings (2) ```r #The code on the right selects the name column of all planets #that have rings. #Adapt the code so that instead of only the name column, #all columns for planets that have rings are selected. # Definition of vectors name <- c("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune") type <- c("Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Gas giant", "Gas giant", "Gas giant", "Gas giant") diameter <- c(0.382, 0.949, 1, 0.532, 11.209, 9.449, 4.007, 3.883) rotation <- c(58.64, -243.02, 1, 1.03, 0.41, 0.43, -0.72, 0.67) rings <- c(FALSE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE) # Create a data frame from the vectors planets_df <-data.frame(name,type,diameter,rotation,rings) planets_df # Select the rings variable from planets_df rings_vector <- planets_df$rings # Print out rings_vector rings_vector # Adapt the code to select all columns for planets with rings planets_df[rings_vector,] ``` \#10-Only planets with rings but shorter ```r #Use subset() on planets_df to select planets that have #a diameter smaller than Earth. #Because the diameter variable is a relative measure of #the planet's diameter #w.r.t that of planet Earth, your condition is diameter < 1. # Definition of vectors name <- c("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune") type <- c("Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Gas giant", "Gas giant", "Gas giant", "Gas giant") diameter <- c(0.382, 0.949, 1, 0.532, 11.209, 9.449, 4.007, 3.883) rotation <- c(58.64, -243.02, 1, 1.03, 0.41, 0.43, -0.72, 0.67) rings <- c(FALSE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE) # Create a data frame from the vectors planets_df <-data.frame(name,type,diameter,rotation,rings) planets_df # Select planets with diameter < 1 subset(planets_df,subset=diameter<1) ``` \#11-Sorting ```r #Experiment with the order() function in the console. #Click 'Submit Answer' when you are ready to continue. # Play around with the order function in the console cevi<-c(10,100,9) order(cevi) cevi[order(cevi)] ``` \#12-Sorting your data frame ```r #Call order() on planets_df$diameter in no #4 #(the diameter column of planets_df). Store the result as positions. #Now reshuffle planets_df with the positions vector as row indexes #inside square brackets. Keep all columns. Simply print out the result. # planets_df is pre-loaded in your workspace # Use order() to create positions # Definition of vectors name <- c("Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune") type <- c("Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Terrestrial planet", "Gas giant", "Gas giant", "Gas giant", "Gas giant") diameter <- c(0.382, 0.949, 1, 0.532, 11.209, 9.449, 4.007, 3.883) rotation <- c(58.64, -243.02, 1, 1.03, 0.41, 0.43, -0.72, 0.67) rings <- c(FALSE, FALSE, FALSE, FALSE, TRUE, TRUE, TRUE, TRUE) # Create a data frame from the vectors planets_df <-data.frame(name,type,diameter,rotation,rings) planets_df positions <- order(planets_df$diameter) # Use positions to sort planets_df planets_df[positions,] ``` --- # 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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