一、各种方法介绍
Counter 统计个数 elements most_common subtract
defaultdict 字典默认值
ChainMap 合并多个映射对象（字典）
OrderdDict 有顺序的字典
deque 双向队列，可限制长度 append,appendleft,ratote
namedtuple 命名元祖
二、代码部分
from collections import Counter, defaultdict, ChainMap, OrderedDict, deque, namedtuple
"1.Counter"
# 三个方法，在前面的博客词频统计有学习过。
s = \'de8g love python so much\'
counter = Counter(s)
# print(counter, type(counter))
# print(list(counter.elements()))
print(counter.most_common(5)) # 排序
counter.subtract(\'o\') # 对某一个统计减少一次
print(counter.most_common(5)) # 排序
"2. 默认字典"
# 默认字典defaultdict 在lambda中学习过
defaultdict(lambda: 0)
defaultdict(lambda: \'abc\')
c = defaultdict(lambda: (3,6))
c[\'a\']
print(c)
# 默认字典在传统的统计里面使用
s = \'de8ug loves you so de8ug loves you so much you so much much \'
# count_spilt = {}
dc_words = defaultdict(int) # 或者 lambda: 0
dc_words[10]
for i in s.split(\' \'):
# if i in count_spilt:
# count_spilt[i] += 1
# else:
# count_spilt[i] = 1
dc_words[i] += 1
print(dc_words)
# 默认字典的赋值为空列表
line = [(1,2),(1,3),(3,6),(4,7),(3,9),(4,9),(5,10)]
# 把相同x的y 追加到列表中
# line_new = {1:[2,3],3:{6,9}}
line_new = {}
for x,y in line:
if x not in line_new:
line_new[x] = [y]
else:
line_new[x].append(y)
print(line_new)
# -----------------------
line_dic = defaultdict(list) # 新做法
for x, y in line:
line_dic[x].append(y)
print(line_dic)
"3. ChainMap "
# 把两个字典组合起来
d1 = {\'debug\':1,"louhui":2,"diaosi":3}
d2 = {1: [2, 3], 3: [6, 9], 4: [7, 9], 5: [10]}
chain = ChainMap(d1,d2)
d3 = {\'louhui\':\'shuai\', \'caoyu\':4, 1:"1"}
chain.update(d3)
print(chain)
"4. OrderDict"
# 在python3 字典就是有序的，但是我们不能依赖他，可能会变化
# 传统做法
dict2 = {\'\': 2,\'a\': 3,\'de8ug\': 2,\'e\': 8,\'k\': 9,\'loves\': 2,\'much\': 3,\'so\': 3,\'you\': 3}
keys = dict2.keys()
sorted(keys)
for k in keys:
print(k, dict2[\'e\'])
# 使用OrderDict
dd = {\'banana\': 3, \'apple\':4, \'pear\': 1, \'orange\': 2}
order_dic = Orderdd = {\'banana\': 3, \'apple\':4, \'pear\': 1, \'orange\': 2}
#按key排序
kd = OrderedDict(sorted(dd.items(), key=lambda t: t[0]))
#按照value排序
vd = OrderedDict(sorted(dd.items(),key=lambda t:t[1]))
"5. deque"
# deque - double-end que.双向队列，支持线程安全
de = deque()
de.append(1)
de.append(2)
de.appendleft(3)
print(de)
de1 = deque([1,2,3,4,5,6,7], 7)
print(de1)
de1.rotate(3) # 旋转
print(de1)
# 另外一个作用，tail类型。输出文件的最后几行
def tail_file(filename, n):
with open(filename, \'r\') as f:
return deque(f, n)
print(tail_file(\'/Users/lh/my_learn_python/01-python/123.txt\', 2))
"6. nametuple"
# 就是给元祖每个变量定义一个名字
# 三种命名格式
Point = namedtuple(\'Point\', \'m,n\')
Point = namedtuple(\'Point\', \'m n\')
Point = namedtuple(\'Point\', [\'x\', \'y\'])
# Ponit=namedtuple(\'Point-LH\',\'x,y\')
p = Point(1,2)
print(p)
print(p.x)