【python--字典】 dict 创建的8种方法

# 字典
#{}
dic = {}
print(dic)
print(type(dic))   #  <class \'dict\'>

# 语法格式  {\'xuann\':2,\'lic\':65}
# key --- 键
# value --- 值
# 键值对    一个元素

#  1:创建字典
d1 = dict()
print(d1)       #  空字典 {}

#  2:通过直接赋值创建
di = {\'sop\':2,\'kai\':5}
print(di)      # {\'sop\': 2, \'kai\': 5}

#  3:通过dict函数和关键字创建
die = dict(snian = 1,ajija = 6,)
print(die)     #  {\'snian\': 1, \'ajija\': 6}

#  4:通过二元组创建   通过列表转字典
die =[(15,3),(\'nijao\',3)]
di = dict(die)
print(di)      # {15: 3, \'nijao\': 3}

#  5:zip函数
re = zip([1,2,3,6,5,9])     # zip 后 为可迭代对象
print(re)                     # <zip object at 0x013FF1A8>  迭代器
for i in re:                  #   迭代循环
    print(i)
    # (1,)
    # (2,)
    # (3,)
    # (6,)
    # (5,)
    # (9,)
re = zip([1,2,3,4],[11,22,33,44])
for i in re:
    print(i)
# (1, 11)
# (2, 22)
# (3, 33)
# (4, 44)
re = zip(\'nihao\',[1,2,3,4,5,])
for i in re :
    print(i)
# (\'n\', 1)
# (\'i\', 2)
# (\'h\', 3)
# (\'a\', 4)
# (\'o\', 5)

# print(re.__next__())          # (1,)
#   先用zip函数迭代出元组形式的元素  取出  放到字典里
de = dict(zip(\'mijao\',[1,2,35,4,8]))
print(de)
# {\'m\': 1, \'i\': 2, \'j\': 35, \'a\': 4, \'o\': 8}

#  6:通过字典的推导式 创建
# lis = [i*2 for i in range]     list 推导式
dic = {str(i) : i*2  for i in range(9)}  #dict 推导式
print(dic)
#{\'0\': 0, \'1\': 2, \'2\': 4, \'3\': 6, \'4\': 8, \'5\': 10, \'6\': 12, \'7\': 14, \'8\': 16}

#  7:用 dict.fromkeys
#通常用来初始化字典，设置value的默认值
di = dict.fromkeys(\'nihao\',3)          # {k:value,k:value,k:value,........}
print(di)
# {\'n\': 3, \'i\': 3, \'h\': 3, \'a\': 3, \'o\': 3}

#  8: 其他方式
l = [\'x\',1,\'y\',2,\'o\',5]
de = dict(zip(l[::2],l[1::2]))
print(de)
# {\'x\': 1, \'y\': 2, \'o\': 5