python推导式

基本格式为：

expression for item in sequence if condition

names = ['大湘菜', '小湘菜', '巨大湘菜', '微小湘菜']
# 列表
new_names = [name.upper() for name in names if len(name) > 3]
print(new_names)
print(type(new_names))
# 字典
new_dict = {name: name[0] for name in names}
print(new_dict)
print(type(new_dict))
# 集合
new_set = {len(name) ** 2 for name in names}
print(new_set)  # 自动去掉重复元素
print(type(new_set))
# 元组
new_tuple = (len(name) + 1 for name in names)
print(new_tuple)
print(type(new_tuple))  # 返回生成器对象

结果为：

['巨大湘菜', '微小湘菜']
<class 'list'>
{'大湘菜': '大', '小湘菜': '小', '巨大湘菜': '巨', '微小湘菜': '微'}
<class 'dict'>
{16, 9}
<class 'set'>
<generator object <genexpr> at 0x0000026620A09510>
<class 'generator'>