Coursera Developing Data Products - Quiz 3

data-products-q3.R

# Coursera - Developing Data Products - Quiz 3

# Q1
# Which of the following items is required for an R package to pass R CMD check without any warnings or errors?

# A
# DESCRIPTION file

# Q2
# Which of the following is a generic function in a fresh installation of R, with only the default packages loaded?

install.packages('pryr')
library(pryr)
ftype(lm)
# "function"
ftype(dgamma)
# "function"
ftype(mean)
# "s3"      "generic"
ftype(predict)
# "s3"      "generic"
ftype(show)
# "s4"      "generic"
ftype(colSums)
# "internal"

# A
# mean, predict

# Q3
# What function is used to obtain the function body for an S4 method function?

showMethods(show)
getMethod(show)

# A
# getMethod()

# Q4
# Please download the R package DDPQuiz3 from the course web site. Examine the createmean function implemented in the R/ sub-directory. What is the appropriate text to place above the createmean function for Roxygen2 to create a complete help file?

# A

#' This function calculates the mean
#' 
#' @param x is a numeric vector
#' @return the mean of x
#' @export
#' @examples 
#' x <- 1:10
#' createmean(x)