TDM 20100: Project 1 — Welcome to the CLI!

It’s been a long summer, so let’s start our first project this semester off with a quick review of Anvil. In case you haven’t already, visit ondemand.anvil.rcac.purdue.edu and log in using your ACCESS account credentials. If you don’t already have an account, follow these instructions to set one up. If you’ve forgotten your account credentials or are having other issues related to Anvil, please reach out to [email protected] with as much information as possible about your issue.

Once logged in, start a new Anvil session for a few hours (try not to use more than 3 for the moment) and 1 CPU core.

For this first question, we’re going to have you get used to working with Jupyter. To start, upload this project template to Jupyter and fill in your name and the project number as needed, selecting seminar (not seminar-r) as your kernel.

Then, run the following Python in a code cell. For a more in-depth reminder on working in Jupyter, feel free to take a look at this year’s 10100 project 1 or check out this guide on Jupyter.

Then, in a new code cell, run the following:

The first line, %%bash, is cell magic, which tells our kernel to expect a different language than the default. (In this case, the default is Python and we are telling it to use bash instead.) When using cell magic, it is necessary to have the cell magic as the first line in the cell. If (for instance) a comment is the first thing in the cell, then the cell magic will fail.

The second line consists of echo Hello World!. echo is a Bash command similar to print() in Python, and we have it print "Hello World!"

As for Bash (short for Bourne-Again-SHell), you can think of it as a programming language for the command line. Bash has a lot of handy tools and commands to learn, and the rest of this project will be spent beginning to learn about Bash.

The terminal is what we call the area we typically work with the CLI in. While we can run Bash in our Jupyter notebook (as we did above), you will typically work directly in a terminal and throughout this semester we would recommend that you first run your Bash code in a terminal before copying the finished code over to your Jupyter notebook. To open a terminal on Anvil, open a new tab and select Terminal, where you’ll be greeted with a window that looks somewhat like the following (albeit jaxmattfair will be replaced by your access username.)

Try typing echo Hello World! and hitting enter. You should see the terminal print "Hello World!" before waiting for another command.

To get credit for this question, write a command using echo that prints "Hello X!" where "X" is replaced with your name. Be sure to copy your finished command into your Jupyter notebook and run it using cell magic to get credit for your work.

Knowing how to navigate in the shell is helpful. A few notes:

Absolute paths start with a '/', like this:

/anvil/projects/tdm/data/flights/subset/

Relative paths do not start with a '/', like this:

subset

The 'cd' command is used to change directories.

By default, 'cd' just changes your location back to your home directory.

You can type 'cd' with absolute paths or relative paths, for instance:

or like this:

If you want to go back to a directory one level higher, type 'cd ..'

For instance, try this, which first moves our location to the flight subset directory, and then back to the flights directory, and then back to the data directory.

The pwd command prints the working directory.

The ls command prints the contents of the working directory, with only the file names.

Dr Ward likes to run ls -la (those are lowercase letter L’s, not number 1’s), which shows information about the files in the directories.

Dr Ward also uses pwd a lot, to make sure that he is working in the directory that he intended to be working in.

Which years of flight data are in the directory:

/anvil/projects/tdm/data/flights/subset/?

Which years of flight data are in the directory:

/anvil/projects/tdm/data/flights/?

In which of the two directories are the files bigger in size?

We can use the head and the tail commands to see the top lines and the bottom lines of a file. By default, we see 10 lines of output, in each case. We can use the -n flag to change the number of lines of output that we see. For instance:

shows the first 6 lines of the 1987.csv file in the flights subset directory. This includes the header line and also the information about the first 5 flights.

The cut command usually takes two flags, namely:

the -d flag that indicates how the data in a flag is delimited (in other words, what character is placed between the pieces of data), and

the -f flag that indicates which fields we want to cut.

Use the cut command to extract all of the origin airports and destination airports from the 1987.csv file in the flights subset directory, and store the resulting origin and destination airports into a file in your home directory.

You can save the results of your work in bash in a file in your home directory like this:

Use the grep command to find data in the 1987.csv file in the flights subset directory that contain the pattern IND. Save all of the lines of that 1987.csv file into a new file in your home directory called indyflights.csv.

Now consider the file:

/anvil/projects/tdm/data/icecream/combined/reviews.csv

Use the grep command to extract all of the lines from this file that contain the word terrific and store these reviews in a new file called terrificreviews.csv in your home directory.

If you look at the first line of the file:

/anvil/projects/tdm/data/icecream/combined/reviews.csv

you will see that field 5 of each line has the number of stars for that product review.

Among (only) the reviews in the terrificreviews.csv file, how many of the reviews had only 1 star? How many had 4 stars? How many had 5 stars?