Slides

# Intro to Python
## Week 10
### Dictionaries and exceptions

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## Agenda

- Tues: Dictionaries (Ch 12)
- Thurs: Exceptions (Ch 13)

notes:

- [ ] dict for classify_text "mapping"
- [ ] poor-mans machine learning using dict lookup
- [ ] `.get()`
- [ ] global dict with game data
- [ ] `dict`s as kwargs instead of mutable args
- [ ] insidious semantic/logic `dict` errors (mutable default args to functions)
- [ ] `__dict__`

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## Auto-lint with ruff

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```python
def tokenize(text):
    return str(text).split()
```

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```python
def classify_text(text):
    """ Recognize user intent: yes, no, or unknown

>>> classify_text('Y')
    'yes'
    >>> classify_text('NOWAY')
    'no'
    >>> classify_text("I don't know!!")
    'unknown'
    """
    words = tokenize(text.lower())
    score = 0
    for w in words:
        score += int(w[0] == 'y')
        score -= 1 * int(w[0] == 'n')
    score /= len(words)
    if score > 0.5:
        return 'yes'
    elif score < -.1:
        return 'no'
    return 'unknown'
```

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```python
rules = {
    'yes': {
        'y': 1,
        'yea': 1,
        'sure': 1,
        'ok': 1,
        },
    'no': {
        'n': 1,
        'nope': 1,
        },
    'exit': {
        'x': 1,
        'q': 1,
        'quit': 1,
        },
}
```

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```python
def classify_text(text):
    """ Recognize user intent: yes, no, unknown, left, right

>>> classify_text('Y')
    'yes'
    >>> classify_text('NOWAY')
    'no'
    """
    tokens = tokenize(text.lower())
    category_scores = {}
    for tok in tokens:
        for category, rule in rules.items():
            for alias, points in rule.items():
                if tok == alias:
                   category_scores[category] = category_scores.get(category, 0) + points
    find_key_of_max_value(category_scores)    
```

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```python
def find_key_of_max_value(d):
    """ find the maximum value key in a dictionary

>>> find_max_value({'yes': 1, 'no': 2, 'unknown': 3})
    'unknown'
    """
    max_value = 0
    for k, v in d.items():
        if v > max_value:
            max_value = v
            key_of_max_value = k
    return key_of_max_value
```

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```python
def find_max_value(d):
    """ find the maximum value key in a dictionary

>>> find_max_value({'yes': 1, 'no': 2, 'unknown': 3})
    'unknown'
    """
    value_key_pairs = [(v, k) for (k, v) in d.items()]
    # return sorted(value_key_pairs)[-1][1]
    return max(value_key_pairs)[1]
```

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