自定义Python unique()函数循环异常：首次迭代后停止执行问题

核心问题 #

• 函数内部依赖全局变量l而非传入的参数x，逻辑耦合性强
• return语句写在外层for循环内部，第一次迭代就直接返回结果，导致后续循环无法执行
• count变量未在每次外层循环中重置，会累计所有元素的计数，结果错误

修正后的代码 #

def uni(x):
    # 基于传入的参数创建唯一元素集合，避免依赖全局变量
    unique_items = set(x)
    result = []
    for item in unique_items:
        count = 0  # 每次遍历新元素时重置计数
        for element in x:
            if item == element:
                count += 1
        result.append(f"{item}: {count}")
    # 循环结束后返回所有结果，用换行符拼接成字符串
    return '\n'.join(result)


l = ["business", "business", "business", "economy", "economy", "economy", "economy", "business", "premium", "business", "first"]
xx = uni(l)
print(xx)

输出结果 #

business: 5
economy: 4
first: 1
premium: 1

额外优化思路 #

如果只是统计列表元素的出现次数，Python内置的collections.Counter可以更简洁实现：

from collections import Counter

l = ["business", "business", "business", "economy", "economy", "economy", "economy", "business", "premium", "business", "first"]
counts = Counter(l)
for item, num in counts.items():
    print(f"{item}: {num}")

内容的提问来源于stack exchange，提问作者Raakin Ahmed