Assignment Format

# 2.1 example
w = 2
h = 3
l = 1.5
w
h
l
#2.2 example 
volume = w * h * l
volume

Setup

Load packages

  • Make sure that tidyverse is downloaded on the machine you’re using

    • You can check this by clicking on the Packages tab in the Files, Plots, Packages… panel and scrolling down

    • If you need to download the package, copy the following code into your Console panel and run it **Do not put it in your homework script*

    • install.packages("ggplot2")

  • Copy the following code into the beginning of your homework script to load the ggplot2 package:

# load libraries
library(tidyverse)

Data

Download the galapagos-finches.csv data from D2L and put it in your data/ folder in your Class R project.

Read the data file into R using the following command:

# read in full data set
finch <- read.csv("data/galapago-finches.csv")

Exercises: dplyr and ggplot2

Problem 0: get to know the data

0.1 Use head() to print out the first few rows of the finch data.

0.2 Print out the last few rows of the finch data.

0.3 Print out the names of the columns in the finch data.

0.4 Use select() to print out only the species column.

0.5 Use select() to print out the year, species and blength columns, in that order.

0.6 Use arrange() to print out the finch data in order based on the blength column.

0.7 Use arrange() to print out the finch data in order based on the species, year, and bdepth columns, in that order.

0.8 Use mutate() to add a new column called beak_area, and have its value equal to blength * bdepth.

0.9 Use summarize to calculate the average blength across the whole finch data set.

0.10 Use group_by() and summarize to calculate the average blength for each species in finch data set.

Problem: 1 Plot one continuous variable

1.1 Make a histogram of the blength column.

1.2 Make a histogram of the blength column and give it a descriptive title (5-7 words) and change the the x-axis label to be more easily read and include the units (mm).

1.3 Make a histogram of the blength column with 100 bins.

1.4 Make a histogram of the blength column where the binwidth is 1.

1.5 Make a boxplot of the blength.

1.6 Make a boxplot of the blength but change the fill color to one of your choice. (See a list of color names available in ggplot)

Problem 2: Plot with grouping variables

2.1 Make a boxplot of the blength, but have the fill color vary based on the species.

2.2 Make a boxplot of the blength, but have the fill color vary based on the year collected. (Careful of continuous vs. categorical variables. )

2.3 Make a boxplot of the blength, but have the fill color vary based on the year, and have species mapped to the y-axis.

Problem 3: Plot two continuous variables

3.1 Use geom_point() to make a scatter plot with blength on the x-axis, and bdepth on the y-axis.

3.2 Use geom_point() to make a scatter plot with blength on the x-axis, and bdepth on the y-axis. Also include a linear regression on the plot for the whole data set (there should be one line on your graph).

3.3 Use geom_point() to make a scatter plot with blength on the x-axis, and bdepth on the y-axis. Also have the color of the points relate to the species, and include a linear regression on the plot for each species separately (there should be 2 lines on your graph).

3.4 Repeat the graph you made in 3.3 above but include a separate facet for each year of data.

Problem 4: dplyr + ggplot

4.1 Use mutate() to create a new variable in the finch data set. This new variable should be equal to beak length \(\times\) beak depth. Make a plain histogram showing the distribution of your new variable.

4.2 Do the same thing as in 4.1, but this time, only plot the data from 1975, and map the fill color to the species variable.

4.3 Do the same thing as in 4.2, but add a descriptive title and x-axis label.

4.4 Do the same thing as in 4.1, but this time have the fill color mapped to species, and have a facet for each year.