Python 基础与笔记（4）

原创于 2018-01-03 11:22:34 发布 · 248 阅读

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本文通过具体的Python代码示例介绍了如何定义和使用带有*args和**kwargs的函数，并展示了生成器的基本用法，包括如何创建和遍历生成器以高效地处理数据。

"yahoo!" if 3 > 2 else 2  # => "yahoo!"

with open("myfile.txt") as f:    
	for line in f:
        print line
####################################################
# Functions
####################################################
def varargs(*args):
    return args
varargs(1, 2, 3)  # => (1, 2, 3)
def keyword_args(**kwargs):
    return kwargs
keyword_args(big="foot", loch="ness")  # => {"big": "foot", "loch": "ness"}
def all_the_args(*args, **kwargs):
    print args
    print kwargs
"""
all_the_args(1, 2, a=3, b=4) prints:
    (1, 2)
    {"a": 3, "b": 4}
"""
####################################################
values = (-x for x in [1, 2, 3, 4, 5])
for x in values:
    print(x)  # prints -1 -2 -3 -4 -5 to console/terminal
# You can also cast a generator comprehension directly to a list.
values = (-x for x in [1, 2, 3, 4, 5])
gen_to_list = list(values)
print(gen_to_list)  # => [-1, -2, -3, -4, -5]