Thu Sep 26

The assignment for Tuesday has been posted.

Questions about anything?

more lists, strings, files

Today we'll finish the material in chapter 5 in the text, covering strings, lists, and files.

Review from Tuesday

• indeces : 'abcde'[2] , 'abcdefghi'[3:7]
• string and list methods : dir([]), dir("") ... and their documentation
• "modification in place" vs "return new value"
• loops over strings or lists
• accumulator coding pattern : building up a new string or list piece by piece
• converting a string to a list
  • list("one two three")
  • "one two three".split()
• converting a list to a string :
  • str(['a', 'b', 'c])
  • ''.join(['a', 'b', 'c'])

What's left to talk about

• string formatting
• file input/output

We'll work through some examples or two in class.

A certain CS professor gives 5-point quizzes that are graded on the scale 
5-A, 4-B, 3-C, 2-D, 1-F, 0-F. Write a program that accepts a quiz score 
as an input and prints out the corresponding grade.

write a program that reads in a file of numbers with 
commas between them, and writes a summary with lines 'count:_' 
and 'average:_'.

rewrite the chaos program from chapter 1 in several ways :
  (a) print the numbers in a nicely aligned table
  (b) output the numbers to a file
  (c) read the inputs from a file 

Translate a lowercase word into its cipher, with each letter incremented by 1 - encoding.
Write another program that translates it back - decoding.

Aside: unix command line input/output redirection as an alternative way to do file input output

$ python yourprogram.py < input.txt > output.txt

Aside: running python: "python mything.py" vs "import mything".

in class

... we wrote the attached file_summary.py program as an example.

attachments

		last modified	size
	file_summary.py	Fri Oct 31 2025 11:36 am	830B