SelectingCases.R

# File:   SelectingCases.R
# Course: R: An Introduction (with RStudio)

# INSTALL AND LOAD PACKAGES ################################

library(datasets)  # Load/unload base packages manually

# LOAD DATA ################################################

head(iris)

# ALL DATA #################################################

hist(iris$Petal.Length)
summary(iris$Petal.Length)

summary(iris$Species)  # Get names and n for each species

# SELECT BY CATEGORY #######################################

# Versicolor
hist(iris$Petal.Length[iris$Species == "versicolor"],
  main = "Petal Length: Versicolor")

# Virginica
hist(iris$Petal.Length[iris$Species == "virginica"],
  main = "Petal Length: Virginica")

# Setosa
hist(iris$Petal.Length[iris$Species == "setosa"],
  main = "Petal Length: Setosa")

# SELECT BY VALUE ##########################################

# Short petals only (all Setosa)
hist(iris$Petal.Length[iris$Petal.Length < 2],
  main = "Petal Length < 2")

# MULTIPLE SELECTORS #######################################

# Short Virginica petals only
hist(iris$Petal.Length[iris$Species == "virginica" & 
  iris$Petal.Length < 5.5],
  main = "Petal Length: Short Virginica")

# CREATE SUBSAMPLE #########################################

# Format: data[rows, columns]
# Leave rows or columns blank to select all
i.setosa <- iris[iris$Species == "setosa", ]

# EXPLORE SUBSAMPLE ########################################

head(i.setosa)
summary(i.setosa$Petal.Length)
hist(i.setosa$Petal.Length)

# CLEAN UP #################################################

# Clear environment
rm(list = ls()) 

# Clear packages
detach("package:datasets", unload = TRUE)  # For base

# Clear plots
dev.off()  # But only if there IS a plot

# Clear console
cat("\014")  # ctrl+L

# Clear mind :)