{
  rm(list=ls());                         # clear the Environment tab
  options(show.error.locations = TRUE);  # show line numbers on error
  library(package=ggplot2);              # include all GGPlot2 functions
  
  #### Creating three objects to put in a List
  someAnimals = c("llama", "guanaco", "alpaca", "goat");  
  someNumbers = matrix(nrow=2, ncol=3, seq(from=30, to=4, length.out=6))
  weatherData = read.csv(file="data/Lansing2016NOAA.csv");
 
  #### Create a new List with the three objects above 
  listAtOnce = list(someAnimals, someNumbers, weatherData);
  
  #### Same List but give a name to each of the objects
  listAtOnce2 = list(animals = someAnimals,
                     numbers = someNumbers, 
                     weather = weatherData);
  
  #### Create a new (and empty) List
  listDynamic = list();
  
  ### Append an object to the List -- this will append each value within the objects as a separate object
  listDynamic2  = append(listDynamic, someAnimals);  

  ### Append an object to the List as a whole object
  listDynamic3 = append(listDynamic, list(someAnimals));
  
  ### Give a name to the appended object 
  listDynamic4 = append(listDynamic, list(animal = someAnimals));
  
  ### Add the other two objects to the list with names 
  listDynamic5 = append(listDynamic4, list(numbers=someNumbers));
  listDynamic5 = append(listDynamic5, list(weather=weatherData));
  
  #### Subsetting a List
  anim1 = listDynamic5[["animal"]];
  anim2 = listDynamic5$animal;
  
  dewPoint1 = listDynamic5$weather$dewPoint;
  dewPoint2 = listDynamic5[["weather"]][["dewPoint"]];
  dewPoint3 = listDynamic5[["weather"]]$dewPoint;
  
  #### Subsetting by numeric placement
  anim3 = listDynamic5[[1]];
  dewPoint4 = listDynamic5[[3]][[7]];
  
  #### Subsetting using [ ] -- this returns a List, which is not very useful:
  anim4 = listDynamic5["animal"];
  
  #### A Humidity vs. Temperature plot with linear regression ####
  plot1 = ggplot( data=weatherData ) +
    geom_point( mapping=aes(x=avgTemp, y=relHum) ) +
    geom_smooth( mapping=aes(x=avgTemp, y=relHum), 
                 method="lm" ) +
    labs( title="Humidity vs Temperature",
          subtitle="Lansing, MI -- 2016",
          x = "Average Temperatures (Fahrenheit)",
          y = "Relative Humidity") +
    scale_x_continuous( breaks = seq(from=10, to=80, by=10) ) +
    theme_bw() +
    theme( axis.text.x=element_text(angle=90, vjust=0.5) );
  plot(plot1);
  
  model1 = lm(formula=weatherData$avgTemp~weatherData$relHum);    
  
  #### Subsetting model1 
  intercept = model1$coefficients["(Intercept)"];
  first10Residuals = model1$residuals[1:10];
  every20thFitted = model1$fitted.values[seq(from=1, to=366, by=20)];
  
  #### Changing values in the plot
  plot2 = plot1;
  
  plot2$theme$text$colour = "red";
  plot2$labels$x = "Average Temperature (\u00B0F)"; # \u00B0 is Unicode for the degree symbol
  plot2$theme$line$linetype = 2;
  plot2$theme$line$size = 0.8;
  plot(plot2);
}