Python中集合推导式的实现

{expression for item in iterable if condition}

even_numbers = {x for x in range(1, 11) if x % 2 == 0}
print(even_numbers)  # 输出: {2, 4, 6, 8, 10}

my_string = "hello world"
unique_chars = {char for char in my_string if char.isalpha()}
print(unique_chars)  # 输出: {'d', 'e', 'h', 'l', 'o', 'r', 'w'}

numbers = [-1, 0, 1, 2, -2, 3, -3]
positive_numbers = {num for num in numbers if num > 0}
print(positive_numbers)  # 输出: {1, 2, 3}

set1 = {1, 2, 3, 4, 5}
set2 = {3, 4, 5, 6, 7}
intersection = {x for x in set1 if x in set2}
print(intersection)  # 输出: {3, 4, 5}

matrix = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
]
large_numbers = {num for row in matrix for num in row if num > 5}
print(large_numbers)  # 输出: {6, 7, 8, 9}

survey_results = [
    {"user_id": 1, "response": "yes"},
    {"user_id": 2, "response": "no"},
    {"user_id": 3, "response": "yes"},
    {"user_id": 1, "response": "yes"}
]

yes_users = {result["user_id"] for result in survey_results if result["response"] == "yes"}
print(yes_users)  # 输出: {1, 3}

data_sources = [
    {"source": "A", "data": [1, 2, 3, 4]},
    {"source": "B", "data": [3, 4, 5, 6]},
    {"source": "C", "data": [5, 6, 7, 8]}
]

unique_data = {item for source in data_sources for item in source["data"]}
print(unique_data)  # 输出: {1, 2, 3, 4, 5, 6, 7, 8}

raw_data = ["abc", "def", "", "abc", None, "ghi"]
cleaned_data = {item for item in raw_data if item}
print(cleaned_data)  # 输出: {'abc', 'def', 'ghi'}

query_results = [
    {"id": 1, "name": "Alice"},
    {"id": 2, "name": "Bob"},
    {"id": 3, "name": "Alice"}
]

unique_names = {result["name"] for result in query_results}
print(unique_names)  # 输出: {'Alice', 'Bob'}