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STAT605: Data Science Computing Project Homework 1: Text Editors
This homework will give you some exposure to the text editors vim and emacs. When doing these exercises, please use the commands on the reference sheets at
www.stat.wisc.edu/~jgillett/605/emacs/emacs.html
and
https://vim.rtorr.com/
The goal is not simply to get the specified tasks done, but rather to do so using the functionality available in emacs and vim, so try do the tasks elegantly, using the tools provided by the editors.
You may ask your classmates, TA or instructors for help with these exercises. If you collaborate with classmates, please include their names and their primary @wisc.edu email addresses on the line after your name in your submission files.
1 Editing text in emacs
This problem will give you some practice using emacs to edit text.
1. Start emacs on your Linux virtual machine.
2. Use emacs to make a new directory, 1 (for “homework 1”), in your ~/Desktop directory. That is, make the new directory ~/Desktop/1.
3. Download baby_T_Test.R and move it to your 1 directory.
(a) Read baby_T_Test.R into emacs.
(b) The code has four problems with parentheses. Indent the buffer. The first indenting irregularity indicates a parentheses problem on the previous line. Fix it by adding a parenthesis. Repeat until the whole file is indented correctly.
(c) Save the file as baby_t_test.R (note “T_Test” changed to “t_test”).
(d) Make these replacements in baby_t_test.R.
- Inside the baby.t.test() function, replace each r (where r indicates the list being set up as a return value) with return.list.
- Replace each occurrence of three newlines with two newlines. Hint: We can’t use Enter to type a newline in the minibuffer, as it ends the minibuffer’s input. Use C-q C-j to type a literal newline into the minibuffer. C-q runs quoted-insert, which allows inserting a literal newline in linux (newline is C-j, the decimal ASCII code 10), a control character, etc. There are still sequences of three newlines remaining, so jump to the top of the buffer and do it again. (We’ll see a way to do these two steps in one step after we study regular expressions soon).
(e) Use the emacs R buffer to:
i. Run the chunk of code consisting of the baby.t.test() function definition.
ii. Run the “test case” code one line at a time. Note that the p.value test fails. The bug is that I mistakenly used df=n instead of df=n-1 in my call to pt() in baby.t.test(). Fix this bug, run the baby.t.test() chunk again, and run the test code (one line at a time) again.
iii. Run the entire buffer.
(f) Kill the R buffer. Start it again.
i. Find 3 + 4 (just type it at the R command prompt).
ii. Run source("baby_t_test.R") (just type it at the R command prompt).
(g) Kill the R buffer again and exit emacs.
4. Download gettysburg1.txt and gettysburg2.txt to your 1 directory.
(a) Use Multiple Windows (in a single emacs session) to split emacs vertically (into halves) and vertically again (now you have one half and two quarters).
(b) Resize the windows so they all have the same size. (Oops, I forgot to demonstrate resizing windows, but it’s on the reference sheet under Multiple Windows: C-x ^ will make the current subwindow taller. Do it a few times in each of the quarter-sized windows until you have three one-third-sized windows.)
(c) Open gettysburg1.txt in the first window and gettysburg2.txt in the second. Open (the new empty file) gettysburg_emacs.txt in the third window.
(d) Use cut, copy, and paste commands to reassemble the Gettysburg Address from its segments in the first two windows into a whole in the third window. Handle each “paragraph” in the downloaded files separately (e.g. lines 1-2 are a paragraph, as is line 3, as are lines 4-6). Save gettysburg_emacs.txt when you are done. Close its buffer.
(e) Return to a single window. Open the Directory Editor on . (“dot”), the current directory. i. Rename gettysburg_emacs.txt to GettysburgAddress_emacs.txt. ii. Find (open) GettysburgAddress_emacs.txt again.
(f) Kill the rectangle consisting of the line numbers and spaces preceding each line of the address. Save GettysburgAddress_emacs.txt again.
2 Editing text in vim
This problem will give you more experience using vim, and will show you a few useful tricks for getting things done quickly.
1. Make sure gettysburg1.txt and gettysburg2.txt are still in your 1 directory (download them again, if not).
(a) Use vim’s windowing system to split the screen horizontally once, and then vertically once (we didn’t discuss this latter command in the videos– :split splits horizontally; :vsplit splits vertically). Your screen should be split into one half and two quarters.
(b) Open gettysburg1.txt in the first window and gettysburg2.txt in the second. Open (the new empty file) gettysburg_vim.txt in the third window.
(c) Use cut (dd), copy (yy), and paste (p or P) commands to reassemble the Gettysburg Address from its segments in the first two windows into a whole in the third window. Handle each “paragraph” in the downloaded files separately (e.g. lines 1-2 are a paragraph, as is line 3, as are lines 4-6). Save gettysburg_vim.txt when you are done and close the windows. Return to the command line and do the following (or try using vim’s :!shell_cmd to run the command shell_cmd without leaving vim):
i. Rename gettysburg_vim.txt to GettysburgAddress_vim.txt.
ii. Remove gettysburg1.txt and gettysburg2.txt.
iii. Open GettysburgAddress_vim.txt in vim again.
(d) Use visual block mode to delete the line numbers and spaces preceding each line of the address. Save GettysburgAddress_vim.txt again.
(e) Exit vim.
2. Download the file semicolons.c from the course webpage and save it to your 1 directory. Open it in vim.
(a) semicolons.c is a snippet of C code. Don’t worry if you’ve never coded in C before! All you need to know for this excise is that every line of C needs to end in a semicolon (;). So, for the code in semicolons.c to run, we need to put a semicolon at the end of each line. Go to the first line, type A to enter insert mode at the end of the line, type a semicolon (;), and press escape () to return to normal mode.
(b) Now, we want to perform this same operation on every line of semicolons.c. The period (.) repeats the last operation we performed. Move the cursor to the second line and press (.). The result should be that the second line now has a semicolon at the end, too.
(c) We could put a semicolon at the end of every line by moving the cursor to each line, one at a time, and pressing ., but there’s a better way. We can run a command on multiple lines by selecting them in visual line mode, and then telling vim to execute the . command.
1) Put your cursor on the third line, then type V to enter visual line mode.
2) Highlight from line 3 to the end of the file (a shortcut for this is to type G).
3) Type :’<,’>normal . and hit enter. This tells vim to take each highlighted line, and call the normal-mode command ..
(d) The most typical formula for editing in vim is to combine an operator (e.g., d, x or y) with a motion (i.e., specifying a location, such as the next beginning of a word or the end of the current line). We saw the dd command in lecture, but the d command has a lot more options available. For example, we can write dw to delete from the cursor to the next start of a word, or d^ to delete from the cursor to the beginning of the line. An especially useful command is the daw command. It deletes the current word under the cursor (it’s easy to remember– daw stands for “delete a word”). Use the daw command to delete the word approximately from the last line of semicolons.c.
(e) Type the command :wq to save your changes and quit vim.
3. Download the file hw_snippet.tex to your 1 directory and open it in vim.
(a) .tex is the standard extension for LATEX, a markdown language for creating pdfs. hw_snippet.tex contains the LATEX code for a snippet of this homework assignment. I make a habit of putting lots of new lines (i.e., the “return” or “enter” key) in my .tex files, but some people find this annoying. You can get rid of linebreaks with the J command. Press J once and you’ll notice that the newline at the end of the current line is deleted, and the text on the next line is “joined” to the current line.
(b) We could hit J repeatedly to join all the lines into one, but instead let’s use visual line mode again to apply the J command to every line. Highlight every line of the file using visual line mode, and then type J. The result should be that all the text is joined onto one line. Note that there is some possibility for confusion, here. When we talk about a line in programming, we mean a length of text, ended by a new line (i.e., the “return” or “enter” key). This is in slight contrast with lines in your terminal. By default, your terminal will only display 80 characters per line, and a line that is longer than 80 characters will be displayed on multiple lines in the terminal (you may see this described as wrapped text).
(c) Now, let’s put together a few of the things we saw above. Recall from lecture the search command /XYZ, which searches for the next occurrence of the string XYZ. Search for the string the in the text: type /the and hit enter. This will move the cursor to the next occurrence of the string the. Type the command daw to delete it. Type n to move to the next occurrence of the and type . to repeat the previous action (i.e., delete the current word). Proceed in this manner to delete all instances of the word the from hw_snippet.tex. Later in the course, we’ll see some more graceful tools for deleting text and performing find-and-replace operations.
(d) Use the command :wq to save your file and quit.
3 Prepare your files for submission
Okay, let’s get your files ready to submit HW1. Start emacs or vim and open the (new empty) file hw1.txt.
1. Type your full name, followed by your primary @wisc.edu email address.
2. If you discussed this homework with any of your classmates, please list their names and primary @wisc.edu email addresses on the next line.
3. Press the “return” key three times to insert two blank lines.
4. Insert your baby_t_test.R file.
5. Type two blank lines.
6. Insert your GettysburgAddress_emacs.txt file.
7. Type two blank lines.
8. Insert your GettysburgAddress_vim.txt file.
9. Type two blank lines. 10. Insert your semicolons.txt file.
11. Type two blank lines.
12. Insert your hw_swnippet.tex file.
13. Search online to find something interesting emacs can do. Summarize it briefly (no more than 100 words) for consideration by the class for a demonstration.
14. Write a short emacs exercise (no more than 100 words) for consideration by the class for a quiz or homework.
15. Search online to find something interesting vim can do. Summarize it briefly (no more than 100 words) for consideration by the class for a demonstration.
16. Write a short vim exercise (no more than 100 words) for consideration by the class for a quiz or homework.
17. Save hw1.txt and exit emacs.
Okay, that’s it– great work! Upload your hw1.txt file via the Canvas “HW1” grades item.