Ex 25: Dictionary Mapping Challenges

Problem​

Dictionary comprehensions are essential for data transformation. Complete the following five tasks:

1. Word Length Map: Map each word in a list to its length.
2. Invert Dictionary: Swap keys and values in a dictionary (e.g., {'a': 1} becomes {1: 'a'}).
3. Truthy Zip: From two lists (keys and values), build a dictionary but only include pairs where the value is truthy (not 0, None, or empty).
4. Score Scaler: Given a dictionary of names and scores, keep only scores above 70 and scale each by 1.1.
5. Character Grouping: Categorize characters of a string into 'vowel' and 'consonant' sets within a dictionary.

Rules​

• For Task 1, use: ["cat", "elephant", "dog", "python"].
• For Task 2, use: {"a": 1, "b": 2, "c": 3}.
• For Task 3, use: keys = ["a", "b", "c", "d"] and values = [1, 0, 3, None].
• For Task 4, use: {"alice": 85, "bob": 60, "charlie": 72, "diana": 55, "eve": 90}.
• For Task 5, use the string "comprehension".

Boilerplate​

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# Task 1: Word Length Map
words = ["cat", "elephant", "dog", "python"]
length_map = {}

# Task 2: Invert Dictionary
original = {"a": 1, "b": 2, "c": 3}
inverted = {}

# Task 3: Truthy Zip
keys = ["a", "b", "c", "d"]
values = [1, 0, 3, None]
truthy_map = {}

# Task 4: Score Scaler
scores = {"alice": 85, "bob": 60, "charlie": 72, "diana": 55, "eve": 90}
scaled_scores = {}

# Task 5: Character Grouping
text = "comprehension"
grouped = {}

Expected output​

{'cat': 3, 'elephant': 8, 'dog': 3, 'python': 6}
{1: 'a', 2: 'b', 3: 'c'}
{'a': 1, 'c': 3}
{'alice': 93.5, 'charlie': 79.2, 'eve': 99.0}
{'vowel': {'e', 'i', 'o'}, 'consonant': {'c', 'h', 'm', 'n', 'p', 'r', 's'}}

Solution​

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# 1. Word Length Map
words = ["cat", "elephant", "dog", "python"]
length_map = {word: len(word) for word in words}

# 2. Invert Dictionary
original = {"a": 1, "b": 2, "c": 3}
inverted = {val: key for key, val in original.items()}

# 3. Truthy Zip
keys = ["a", "b", "c", "d"]
values = [1, 0, 3, None]
truthy_map = {k: v for k, v in zip(keys, values) if v}

# 4. Score Scaler
scores = {"alice": 85, "bob": 60, "charlie": 72, "diana": 55, "eve": 90}
scaled_scores = {name: score * 1.1 for name, score in scores.items() if score > 70}

# 5. Character Grouping
text = "comprehension"
vowels = set("aeiou")
grouped = {
    "vowel": {c for c in text if c in vowels},
    "consonant": {c for c in text if c not in vowels}
}