Coursera Developing Data Products - Quiz 1

data-products-q1.R

# Q1
# Consider the following code for the cars data set
# This function plots distance versus speed, each de-meaned and an associated line of slope s.
library(manipulate)
myPlot <- function(s) {
 plot(cars$dist - mean(cars$dist), cars$speed - mean(cars$speed))
 abline(0, s)
}
# Which of the following code will make a manipulate plot that creates a slider for the slope?
# A
manipulate(myPlot(s), s = slider(0, 2, step = 0.1))

# Q2
# Which of the following code uses the rCharts package to create a sortable and searchable data table for the airquality data set? Assume the rCharts package and the airquality data set have already been loaded into R.
install.packages("devtools")
install.packages("Rcpp")
library(devtools)
library(Rcpp)
install_github('ramnathv/rCharts')
library(rCharts)

# A
dTable(airquality, sPaginationType = "full_numbers")

# Q3
# A basic shiny data product requires:
# A
# A ui.R and server.R file or a A server.R file and a directory called www containing the relevant html files.

# Q4
# What is incorrect about the followig syntax in ui.R?
library(shiny)
shinyUI(pageWithSidebar(  
  headerPanel("Data science FTW!"),  
  sidebarPanel(    
    h2('Big text'),    
    h3('Sidebar')  
  ),  
  mainPanel(      
    h3('Main Panel text')  
  )
))
# A
# Missing a comma in the sidebar panel.

# Q5
# Consider the following code in ui.R
shinyUI(pageWithSidebar(  
  headerPanel("Example plot"),  
  sidebarPanel(    
    sliderInput('mu', 'Guess at the mu',value = 70, min = 60, max = 80, step = 0.05,)
  ), 
  mainPanel(    
    # HERE: Replace newHist with myHist
    plotOutput('newHist')
  )
))

library(UsingR)
data(galton)

shinyServer(  
  function(input, output) {    
    output$myHist <- renderPlot({      
      hist(galton$child, xlab='child height', col='lightblue',main='Histogram')      
      mu <- input$mu      
      lines(c(mu, mu), c(0, 200),col="red",lwd=5)      
      mse <- mean((galton$child - mu)^2)      
      text(63, 150, paste("mu = ", mu))      
      text(63, 140, paste("MSE = ", round(mse, 2)))      
    })      }
)
# Why isn't it doing what we want?
# A
# The server.R output name isn't the same as the plotOutput command used in ui.R.