add python_functional

Author: xianhu

Diff for: README.md

@@ -17,6 +17,8 @@
 ### python_oneline.py: 几个小例子告诉你, 一行Python代码能干哪些事
 
 ### python_requests.py: Python中最好用的爬虫库Requests代码实例
+
+### python_functional.py: Python进阶: 函数式编程实例（附代码）
 ============================================================
 
 ### 您可以fork该项目,并在修改后提交Pull request

Diff for: python_functional.py

@@ -0,0 +1,74 @@
+# _*_ coding: utf-8 _*_
+
+from fn import _
+from operator import add
+from functools import partial, reduce
+
+# 列表解析
+a_list = [item**2 for item in range(5)]
+print(a_list)
+
+# 字典解析
+a_dict = {"%d^2" % item: item**2 for item in range(5)}
+print(a_dict)
+
+# 生成器
+a_generator = (item**2 for item in range(5))
+print(a_generator)
+print(next(a_generator))
+print(next(a_generator))
+
+# iter函数和next函数
+a_list_generator = iter(a_list)
+print(next(a_list_generator))
+print(next(a_list_generator))
+print(type(a_list), type(a_list_generator))
+
+# lambda表达式
+a_func = lambda x, y: x**y
+print(a_func(2, 3))
+
+# map函数
+print(map(abs, range(-4, 5)))
+print(list(map(abs, range(-4, 5))))
+print(list(map(lambda x: x**2, range(5))))
+print(list(map(lambda x, y: x**y, range(1, 5), range(1, 5))))
+
+# reduce函数
+print(reduce(lambda x, y: x+y, range(10)))
+print(reduce(lambda x, y: x+y, range(10), 100))
+print(reduce(lambda x, y: x+y, [[1, 2], [3, 4]], [0]))
+
+# filter函数
+print(filter(None, range(-4, 5)))
+print(list(filter(None, range(-4, 5))))
+print(list(filter(lambda x: x > 0, range(-4, 5))))
+
+# all、any函数
+print(all([0, 1, 2]))
+print(any([0, 1, 2]))
+
+# enumerate函数
+for index, item in enumerate(range(5)):
+    print("%d: %d" % (index, item))
+
+# zip函数
+for a, b in zip([1, 2, 3], ["a", "b", "c"]):
+    print(a, b)
+a_dict = dict(zip([1, 2, 3], ["a", "b", "c"]))
+print(a_dict)
+
+# partial函数
+print(int("10010", base=2))
+int_base_2 = partial(int, base=2)
+print(int_base_2("10010"))
+
+# operator.add函数
+print(reduce(lambda x, y: x+y, range(10)))
+print(reduce(add, range(10)))
+
+# fn的使用
+add_func_1 = (_ + 2)
+print(add_func_1(1))
+add_func_2 = (_ + _ * _)
+print(add_func_2(1, 2, 3))