Homework One: Due Sept. 6 at 5 pm.

First, download your homework. In your RStudio, enter:


dir.create("/cloud/project/homeworks")  
download.file("https://raw.githubusercontent.com/BiologicalDataAnalysis2019/2019/master/homeworks/HomeworkOne.Rmd", destfile = "/cloud/project/homeworks/HomeworkOne.Rmd")

Your homework will now be located in a directory called homeworks.

Each question will direct you to perform a task. Each question that expects code as an answer will have a space for you to enter the code.

You are welcome, and even encouraged, to work with a partner. I do ask, though, that every member submits their own homework. To submit your homework, simply save it. I will see it.

Question One - 1 point.

Load in the surveys.csv data file, and save it to a variable called “surveys”.

#Enter your answer for Question 1 here

Question Two - 1 point

What is the mean hindfoot length? Show your work below:

#Enter your answer for Question 2 here

Question Three - 1 point

Save the hindfoot_length column to its own variable, called hindfoot_vector.

#Enter your answer for Question 3 here

Question Four - 2 points

Calculate the mean of the hindfoot_vector. Does it work?

#Enter your answer for Question 4 here

In your own words, why did it not work?

Question Five - 1 point

Test your idea about why it didn’t work by writing some code that will fix the problem.

#Enter your answer for Question 5 here

Question Six - 2 points

We included an example in class that was a little confusing. Can you explain, in your own words, why the code gives the result it does?

animals <- c("mouse", "rat", "dog", "cat")
animals %in% c("rat", "cat", "dog", "duck", "goat")

## [1] FALSE  TRUE  TRUE  TRUE

Enter your explanation here:

Question Seven - 2 points

I have written some code to calculate the mean of the hindfoot. But it’s not working! Correct my code.

surveys <- read.csv("/cloud/project/data/surveys.csv")
hindfoot_vector <- surveys[7]
hindfoot_mean <- (sum(hindfoot_vector)/length(hindfoot_vector))