# Let us make a sample survey data set using a list of dictionaries.
survey_data = [
    {'name': 'Alice', 'age': 25, 'favorite_color': 'blue', 'likes_pizza': True},
    {'name': 'Bob', 'age': 30, 'favorite_color': 'green', 'likes_pizza': False},
    {'name': 'Cathy', 'age': 22, 'favorite_color': 'red', 'likes_pizza': True},
    {'name': 'Dan', 'age': 28, 'favorite_color': 'blue', 'likes_pizza': True},
    {'name': 'Eva', 'age': 24, 'favorite_color': 'purple', 'likes_pizza': False},
]

print('Here is our sample survey data:')
for entry in survey_data:
    print(entry)
    

# How many responses are there?
count = len(survey_data)
print('Number of survey responses:', count)

# Let us find the average age.
ages = []
for entry in survey_data:
    ages.append(entry['age'])

average_age = sum(ages) / len(ages)
print('Average age is:', average_age)

# Which color is most popular?
color_count = {}
for entry in survey_data:
    color = entry['favorite_color']
    if color not in color_count:
        color_count[color] = 1
    else:
        color_count[color] += 1

print('Color counts:', color_count)

# Let us find out who likes pizza.
pizza_lovers = []
for entry in survey_data:
    if entry['likes_pizza']:
        pizza_lovers.append(entry['name'])

print('People who like pizza:', pizza_lovers)

# Let us filter survey data by age using input()
age_limit = int(input('Enter age limit to find participants older than: '))
older_participants = []
for entry in survey_data:
    if entry['age'] > age_limit:
        older_participants.append(entry['name'])

print('Participants older than', age_limit, ':', older_participants)

# What if someone did not answer one question?
survey_data.append({'name': 'Frank', 'age': 27, 'favorite_color': None, 'likes_pizza': True})
favorite_colors = []
for entry in survey_data:
    if entry['favorite_color'] is not None:
        favorite_colors.append(entry['favorite_color'])

print('Favorite colors with missing values skipped:', favorite_colors)

# Let us update Eva's favorite color to 'pink'.
for entry in survey_data:
    if entry['name'] == 'Eva':
        entry['favorite_color'] = 'pink'

print("Eva's updated survey info:", [e for e in survey_data if e['name'] == 'Eva'])

# Removing Frank's answer since it was blank
survey_data = [entry for entry in survey_data if entry['name'] != 'Frank']
print('Updated survey_data after removing Frank:')
for entry in survey_data:
    print(entry)
    

# Let us find oldest and youngest participant.
ages = [entry['age'] for entry in survey_data]
print('Oldest:', max(ages))
print('Youngest:', min(ages))

# Gather all unique favorite colors.
unique_colors = set(entry['favorite_color'] for entry in survey_data)
print('Unique favorite colors:', unique_colors)

# Looping with enumerate for more info
for index, entry in enumerate(survey_data):
    print('Entry number', index + 1, 'belongs to', entry['name'])
    

# List comprehensions: shorter way to get names who like pizza
pizza_lovers = [entry['name'] for entry in survey_data if entry['likes_pizza']]
print('Pizza lovers using list comprehension:', pizza_lovers)

# Sorting: order by age, youngest first
sorted_by_age = sorted(survey_data, key=lambda x: x['age'])
print('Survey sorted by age:')
for entry in sorted_by_age:
    print(entry['name'], entry['age'])
    

# Filtering: only people who do not like pizza
not_pizza = [entry['name'] for entry in survey_data if not entry['likes_pizza']]
print('People who do not like pizza:', not_pizza)

# Mini-project: Simple summary of the survey
summary = {
    'total_people': len(survey_data),
    'average_age': round(sum(entry['age'] for entry in survey_data) / len(survey_data), 1),
    'most_popular_color': max(
        set(entry['favorite_color'] for entry in survey_data),
        key=lambda c: [entry['favorite_color'] for entry in survey_data].count(c)
    ),
    'pizza_lovers': len([entry for entry in survey_data if entry['likes_pizza']])
}
print('Survey Summary:')
for k, v in summary.items():
    print(k, ':', v)
    

# Mini-project, part 2: Ask user for a color and count who chose it
target_color = input('Type a color to check how popular it was: ')
color_count = 0
for entry in survey_data:
    if entry['favorite_color'] == target_color:
        color_count += 1

print(target_color, 'was chosen by', color_count, 'participant(s).')

# Best practice: handle keys safely to avoid errors
for entry in survey_data:
    color = entry.get('favorite_color', 'No answer')
    print(entry['name'], 'picked', color)
    

# A common mistake: misspelled keys cause errors
try:
    for entry in survey_data:
        print(entry['fav_color'])  # This key does not exist
except KeyError:
    print('Oops! Key does not exist. Check your spelling.')
    

# Extra tip: make a quick stats table for all colors
color_stats = {}
for entry in survey_data:
    color = entry['favorite_color']
    color_stats[color] = color_stats.get(color, 0) + 1

for color, count in color_stats.items():
    print('Color:', color, '| Count:', count)