Outline for October 23, 2024

Reading: text, §4.5, 7
Due: Homework 2, due October 30, 2023

1. Using floating point numbers [roundoff.py]

2. Using random numbers
   1. import random
   2. Problem: compute π by tossing darts at a unit square
   3. First build routine to simulate dart toss at unit square [mc-1.py]
   4. Then build routine to see if co-ordinates are in unit circle [mc-2.py]
   5. Then build routine to read in number of tosses [mc-3.py]
   6. Put it all together [mc-4.py]
   7. Graphics! [mc-5.py]

3. Files
   1. What is a file?
   2. What can you do with it? (For example, read, write, append)
   3. Types of files (text, binary)

4. File Input and Output for text files
   1. Opening and closing: open(filename, mode), close()
   2. Reading: readline(), readlines(), read(), read(n)
   3. Writing: write(str), writelines(list)

5. Exception EOFError — input function encounters an end of file

6. Examples
   1. Print out a named file [fileio1.py]
   2. Print out a named file and prepend line numbers [fileio2.py]
   3. Store the output in filename.lst [fileio3.py]

7. Examples
   1. Put lines in a file in random order [randlines.py]
   2. Read in a list of words from a file, then search it as requested; similar to linear search program [search-1.py]
   3. Now see how many words you checked total [search-1c.py]

8. Dictionary
   1. Collection of key-value pairs

9. Creating dictionaries
   1. Using d = {}
   2. Using d = dict()

10. Methods for dictionaries
    1. k in D: True if dictionary D has key k; else False
    2. D.keys(): list of keys in D
    3. D.values(): list of values in D
    4. D.items(): list of tuples (key, value) in D
    5. D.get(k, d): if key k in D, return associated value; else return d
    6. del D[k]: delete tuple with key k from D
    7. D.clear(): delete all entries in D

11. Example: memos
    1. Remember how slowly the recursive Fibonacci number program rfib.py ran? Here is a faster recursive version that uses memos [rfibmemo.py]

Matt Bishop Office: 2209 Watershed Sciences Phone: +1 (530) 752-8060 Email: [email protected]

ECS 235A, Computer and Information Security Version of October 22, 2024 at 10:38PM

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