updated

kyclark · kyclark · commit b1abe292107f · 2019-06-16T09:48:46.000-07:00
diff --git a/bin/chapters.txt b/bin/chapters.txt
@@ -30,6 +30,7 @@ twelve_days_of_christmas
 war
 anagram
 hangman
+first_bank_of_change
 markov_chain
 hamming_chain
 morse
diff --git a/book.md b/book.md
@@ -4572,7 +4572,148 @@ You lose, loser!  The word was "metromania."
 
 \newpage
 
-# Chapter 33: Markov Chain
+# Chapter 33: First Bank of Change
+
+Write a Python program called `fboc.py` that will figure out all the different combinations of pennies, nickels, dimes, and quarters in a given `value` provided as a single positional argument. The value must be greater than 0 and less than or equal to 100.
+
+````
+$ ./fboc.py
+usage: fboc.py [-h] int
+fboc.py: error: the following arguments are required: int
+$ ./fboc.py -h
+usage: fboc.py [-h] int
+
+First Bank of Change
+
+positional arguments:
+  int         Sum
+
+optional arguments:
+  -h, --help  show this help message and exit
+$ ./fboc.py 0
+usage: fboc.py [-h] int
+fboc.py: error: value "0" must be > 0 and <= 100
+$ ./fboc.py 124
+usage: fboc.py [-h] int
+fboc.py: error: value "124" must be > 0 and <= 100
+$ ./fboc.py 1
+If you give me 1 cent, I can give you:
+  1: 1 penny
+$ ./fboc.py 4
+If you give me 4 cents, I can give you:
+  1: 4 pennies
+$ ./fboc.py 6
+If you give me 6 cents, I can give you:
+  1: 6 pennies
+  2: 1 nickel, 1 penny
+$ ./fboc.py 13
+If you give me 13 cents, I can give you:
+  1: 13 pennies
+  2: 1 dime, 3 pennies
+  3: 1 nickel, 8 pennies
+  4: 2 nickels, 3 pennies
+$ ./fboc.py 27
+If you give me 27 cents, I can give you:
+  1: 27 pennies
+  2: 1 quarter, 2 pennies
+  3: 1 dime, 17 pennies
+  4: 2 dimes, 7 pennies
+  5: 1 nickel, 22 pennies
+  6: 1 dime, 1 nickel, 12 pennies
+  7: 2 dimes, 1 nickel, 2 pennies
+  8: 2 nickels, 17 pennies
+  9: 1 dime, 2 nickels, 7 pennies
+ 10: 3 nickels, 12 pennies
+ 11: 1 dime, 3 nickels, 2 pennies
+ 12: 4 nickels, 7 pennies
+ 13: 5 nickels, 2 pennies
+````
+
+\newpage
+
+## Solution
+
+````
+     1	#!/usr/bin/env python3
+     2	"""Coin combos for value"""
+     3	
+     4	import argparse
+     5	from itertools import product
+     6	from functools import partial
+     7	
+     8	
+     9	# --------------------------------------------------
+    10	def get_args():
+    11	    """Get command-line arguments"""
+    12	
+    13	    parser = argparse.ArgumentParser(
+    14	        description='First Bank of Change',
+    15	        formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    16	
+    17	    parser.add_argument('value', metavar='int', type=int, help='Sum')
+    18	
+    19	    args = parser.parse_args()
+    20	
+    21	    if not 0 < args.value <= 100:
+    22	        parser.error('value "{}" must be > 0 and <= 100'.format(args.value))
+    23	
+    24	    return args
+    25	
+    26	
+    27	# --------------------------------------------------
+    28	def main():
+    29	    """Make a jazz noise here"""
+    30	
+    31	    args = get_args()
+    32	    value = args.value
+    33	    nickels = range((value // 5) + 1)
+    34	    dimes = range((value // 10) + 1)
+    35	    quarters = range((value // 25) + 1)
+    36	    fig = partial(figure, value)
+    37	    combos = [c for c in map(fig, product(nickels, dimes, quarters)) if c]
+    38	
+    39	    print('If you give me {} cent{}, I can give you:'.format(
+    40	        value, '' if value == 1 else 's'))
+    41	
+    42	    for i, combo in enumerate(combos, 1):
+    43	        print('{:3}: {}'.format(i, fmt_combo(combo)))
+    44	
+    45	
+    46	# --------------------------------------------------
+    47	def fmt_combo(combo):
+    48	    """English version of combo"""
+    49	
+    50	    out = []
+    51	    for coin, val in zip(('quarter', 'dime', 'nickel', 'penny'), combo):
+    52	        if val:
+    53	            plural = 'pennies' if coin == 'penny' else coin + 's'
+    54	            out.append('{} {}'.format(val, coin if val == 1 else plural))
+    55	
+    56	    return ', '.join(out)
+    57	
+    58	
+    59	# --------------------------------------------------
+    60	def figure(value, coins):
+    61	    """
+    62	    If there is a valid combo of 'coins' in 'value',
+    63	    return a tuple of ints for (quarters, dimes, nickels, pennies)
+    64	    """
+    65	
+    66	    nickels, dimes, quarters = coins
+    67	    big_coins = (5 * nickels) + (10 * dimes) + (25 * quarters)
+    68	
+    69	    if big_coins <= value:
+    70	        return (quarters, dimes, nickels, value - big_coins)
+    71	
+    72	
+    73	# --------------------------------------------------
+    74	if __name__ == '__main__':
+    75	    main()
+````
+
+\newpage
+
+# Chapter 34: Markov Chain
 
 Write a Python program called `markov.py` that takes one or more text files as positional arguments for training. Use the `-n|--num_words` argument (default `2`) to find clusters of words and the words that follow them, e.g., in "The Bustle" by Emily Dickinson:
 
@@ -4779,7 +4920,7 @@ Advice and Consent of the United States.
 
 \newpage
 
-# Chapter 34: Hamming Chain
+# Chapter 35: Hamming Chain
 
 Write a Python program called `chain.py` that takes a `-s|--start` word and searches a `-w|--wordlist` argument (default `/usr/local/share/dict`) for words no more than `-d|--max_distance` Hamming distance for some number of `-i|--iteration` (default `20`). Be sure to accept a `-S|--seed` for `random.seed`. 
 
@@ -4982,7 +5123,7 @@ Failed to find more words!
 
 \newpage
 
-# Chapter 35: Morse Encoder/Decoder
+# Chapter 36: Morse Encoder/Decoder
 
 Write a Python program called `morse.py` that will encrypt/decrypt text to/from Morse code. The program should expect a single positional argument which is either the name of a file to read for the input or the character `-` to indicate reading from STDIN. The program should also take a `-c|--coding` option to indicate use of the `itu` or standard `morse` tables, `-o|--outfile` for writing the output (default STDOUT), and a `-d|--decode` flag to indicate that the action is to decode the input (the default is to encode it).
 
@@ -5200,7 +5341,7 @@ THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG.
 
 \newpage
 
-# Chapter 36: ROT13 (Rotate 13)
+# Chapter 37: ROT13 (Rotate 13)
 
 Write a Python program called `rot13.py` that will encrypt/decrypt input text by shifting the text by a given `-s|--shift` argument or will move each character halfway through the alphabet, e.g., "a" becomes "n," "b" becomes "o," etc. The text to rotate should be provided as a single positional argument to your program and can either be a text file, text on the command line, or `-` to indicate STDIN so that you can round-trip data through your program to ensure you are encrypting and decrypting properly.
 
@@ -5365,7 +5506,7 @@ The quick brown fox jumps over the lazy dog.
 
 \newpage
 
-# Chapter 37: Tranpose ABC Notation
+# Chapter 38: Tranpose ABC Notation
 
 Write a Python program called `transpose.py` that will read a file in ABC notation (https://en.wikipedia.org/wiki/ABC_notation) and transpose the melody line up or down by a given `-s|--shift` argument. Like the `rot13` exercise, it might be helpful to think of the space of notes (`ABCDEFG`) as a list which you can roll through. For instance, if you have the note `c` and want to transpose up a (minor) third (`-s 3`), you would make the new note `e`; similarly if you have the note `F` and you go up a (major) third, you get `A`. You will not need to worry about the actual number of semitones that you are being asked to shift, as the previous example showed that we might be shifting by a major/minor/augmented/diminished/pure interval. The purpose of the exercise is simply to practice with lists.
 
@@ -5561,7 +5702,7 @@ aba agE | g2g gab | cba agE |1 gED DEg :|2 gED DBG |]
 
 \newpage
 
-# Chapter 38: Word Search
+# Chapter 39: Word Search
 
 Write a Python program called `search.py` that takes a file name as the single positional argument and finds the words hidden in the puzzle grid. 
 
@@ -6190,6 +6331,39 @@ number = 2
 files  = foo, bar
 ````
 
+## Choices
+
+Sometimes you want to limit the values of an argument. You can pass in a `list` of valid values to the `choices` option. 
+
+````
+$ cat appendix/argparse/choices.py
+#!/usr/bin/env python3
+"""Choices"""
+
+import argparse
+
+parser = argparse.ArgumentParser(
+    description='Choices',
+    formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+
+parser.add_argument('color', metavar='str', help='Color', choices=['red', 'yellow', 'blue'])
+
+args = parser.parse_args()
+
+print('color =', args.color)
+````
+
+Any value not present in the list will be rejected and the user will be shown the valid choices:
+
+````
+$ ./choices.py
+usage: choices.py [-h] str
+choices.py: error: the following arguments are required: str
+$ ./choices.py purple
+usage: choices.py [-h] str
+choices.py: error: argument str: invalid choice: 'purple' (choose from 'red', 'yellow', 'blue')
+````
+
 ## Automatic help
 
 The `argparse` module reserves the `-h` and `--help` flags for generating help documentation. You do not need to add these nor are you allowed to use these flags for other purposes. Using the above definition, this is the help that `argparse` will generate:
diff --git a/playful_python.pdf b/playful_python.pdf
