python中三种高阶函数(map,reduce,filter)详解

# 传一个：
def func(i):return i*2
print([i for i in map(func,[1,'2'])]) # [2,'22']

# 传多个
def func2(x,y):return x+y
print([i for i in map(func2,[1,2],[2,3])]) # [3, 5]

# 传一个时
seq=[1,'2']
result=[]
def func(x):return x*2
for i in seq:
	result.append(func(i))
print(result)
# 传多个时
seq1=[1,2]
seq2=[2,3]
result=[]
def func2(x,y):return x+y
for x,y in zip(seq1,seq2):
	result.append(func2(x,y))
print(result)

seq1=[1,2]
seq2=[2,3,4]
result=[]
def func2(x,y):return x+y
for x,y in zip(seq1,seq2):
	result.append(func2(x,y))
print(result) #[3,5]

print([i for i in map(lambda x, y, z: (f'x:{x}', f'y:{y}', f'z:{z}'), [1, 2, 3, 4, 5], [1, 2, 3, 4], [1, 2])])
# [('x:1', 'y:1', 'z:1'), ('x:2', 'y:2', 'z:2')]

	print([i for i in filter(lambda k: str(k).islower(), ['Java', 'Python', 'js', 'php'])])
 	# ['js', 'php']

_list=['Java','Python','js','php']
result=[]
def is_lower(str_obj):return str(str_obj).islower()
for i in _list:
	if is_lower(i):
		result.append(i)
print(result)

def _add(x, y):
	return x + y
	
# 指定initial
print(reduce(_add,[1],3)) # 4
print(reduce(_add, [1, 2], 2)) # 5
# 不指定initial
print(reduce(_add, [1, 2])) # 3
print(reduce(_add,[1])) # 1
print(reduce(_add, [1, 2, 3, 4, 5])) # 15

def fact(n):
	if n == 1:
		return 1
	return n + fact(n - 1)

print(fact(5)) # 15

print(reduce(lambda x, y: x + y, range(1, 6))) # 15

key = "ECU"
file_dict = {'value': 'name',
			 '刷写ECU': 'burn_ecu_version=ecu_name,burn_package_url,(flash_method)',
			 'BD升级ECU': 'bd_ecu_version=ecu_name,doip_package_url',
			 '设置证书': 'set_ecu_certs=set_method,ecu_name,(bench_name)', 'x': {"ECU": "xx"}}

result = {}
for k, v in file_dict.items():
	if key in k:
		result[k] = v
print(result) 
# {'刷写ECU': 'burn_ecu_version=ecu_name,burn_package_url,(flash_method)', 'BD升级ECU': 'bd_ecu_version=ecu_name,doip_package_url'}

print(dict((k, v) for k, v in file_dict.items() if key in k))

from functools import reduce
print(reduce(lambda x, y: x.update(y) or x,
			 [i for i in map(lambda k: {k: file_dict[k]}, filter(lambda k: key in k, file_dict))]))

class GetResource:
	def __init__(self):
		self.result = {}

	def get_resource(self, key_str, data):

		"""
		从dict中获取包含指定key的k,v
		:param key_str:
		:param data:
		:return:
		"""

		if not isinstance(data, (dict, list, tuple)):
			pass
		elif isinstance(data, (list, tuple)):
			for index in data:
				self.get_resource(key_str, index)
		elif isinstance(data, dict):
			for k, v in data.items():
				if isinstance(v, str):
					if key_str in k:
						self.result[k] = v
				else:
					self.get_resource(key_str, v)
		return self.result


print(GetResource().get_resource(key, file_dict))
# {'刷写ECU': 'burn_ecu_version=ecu_name,burn_package_url,(flash_method)', 'BD升级ECU': 'bd_ecu_version=ecu_name,doip_package_url', 'ECU': 'xx'}