Python开发第三篇基本数据类型
Posted Tanglaoer
tags:
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整型 int
__author__ = ‘Tang‘ # 将字符串转换为数字 a = "123" b = int(a) print(b) # 123 # 前面是0的数转换，默认base按照十进制 a = "0011" b = int(a) print(b) # 11 # 通过base,按照指定进制转换为十进制 a = "0011" b = int(a,base=16) c = int(a,base=8) print(b) # 17 print(c) # 9 # bit_length() 表示这个数字的二进制至少用几位来表示 a = 15 # 1111 b = 16 # 10000 c = a.bit_length() d = b.bit_length() print(c) # 4 print(d)# 5 # a = "0b11" # b = int(a) # print(b) # 报错 # a = "123a" # b = int(a) # print(b) # 报错
字符串 str
1 __author__ = "Tang" 2 3 """不要指望一下全背下来""" 4 """必会的：join split find strip upper lower replace""" 5 6 # capitalize() 首字母大写 7 a = ‘tang‘ 8 b = a.capitalize() 9 print(b) # Tang 10 11 # casefold() 大写变小写 12 a = ‘TANg‘ 13 b = a.casefold() 14 print(b) # tang 15 16 # lower() 大写变小写 17 a = ‘TANg‘ 18 b = a.lower() 19 print(b) # tang 20 21 """ 22 casefold() & lower() 的比较 23 1.都能大写变小写 24 2.casefold 比较全面，像一些特殊语言的变换都可以 25 3.lower 只能处理英文转换 26 """ 27 28 # center() 字符串放中间 29 # center(self, width, fillchar=None) width=总长度 fillchar=填充符号(一个字符) 30 a = ‘tang‘ 31 b = a.center(20) 32 c = a.center(20,‘*‘) 33 d = a.center(20,‘唐‘) 34 print(b) # tang 35 print(c) # ********tang******** 36 print(d) # 唐唐唐唐唐唐唐唐tang唐唐唐唐唐唐唐唐 37 38 # count() 统计次数 39 # count(self, sub, start=None, end=None) sub=要统计的字符 start=开始位置 end=结尾位置 以0开始计数 [start,end) 40 a = ‘tanglaoertanglaoer‘ 41 b = a.count(‘a‘) 42 c = a.count(‘ao‘) 43 d = a.count(‘a‘,5,-1) 44 e = a.count(‘r‘,0,-1) 45 f = a.count(‘r‘,0) 46 print(b) # 4 47 print(c) # 2 48 print(d) # 3 49 print(e) # 1 50 print(f) # 2 51 52 # endswith() 判断以什么结尾 53 # endswith(self, suffix, start=None, end=None) suffix=要判断的字符 start=开始位置 end=结尾位置 以0开始计数 [start,end) 54 a = ‘tanglaoer‘ 55 b = a.endswith(‘er‘) 56 print(b) # True 57 58 # expandtabs() 每次取tabsize个，里面有 的补后面的空格 59 # expandtabs(self, tabsize=8) 60 a = ‘tanglaoer ‘ # 这里补三个空格 第一次取tangla 第二次取oer 61 b = a.expandtabs(6) 62 print(b) # tanglaoer | | | 63 print(len(b)) #12 64 65 # find() 寻找 返回所在位置,未找到返回-1 66 # find(self, sub, start=None, end=None) sub=要查找的字符 start=开始位置 end=结尾位置 以0开始计数 [start,end) 67 a = ‘tanglaoer‘ 68 b = a.find(‘a‘) 69 c = a.find(‘a‘,3) 70 e = a.find(‘p‘,3) 71 print(b)# 1 72 print(c)# 5 73 print(e)# -1 74 75 # format 格式化，占位符替换为指定的值 76 # format(self, *args, **kwargs) 77 a = ‘i am {name}‘ 78 print(a) # i am {name} 79 b = a.format(name=‘tang‘) 80 print(b) # i am tang 81 82 a = ‘i am {0},age {1}‘ 83 print(a) # i am {0},age {1} 84 b = a.format(‘tang‘,‘22‘) 85 print(b) # i am tang,age 22 86 87 # format_map() 格式化 88 # format_map(self, mapping) mapping=字典{} 89 a = ‘i am {name}‘ 90 b = a.format_map({‘name‘:‘tang‘}) # 传字典 91 print(b) # i am tang 92 93 # index() 寻找,找不到就报错 94 # index(self, sub, start=None, end=None) sub=要查找的字符 start=开始位置 end=结尾位置 以0开始计数 [start,end) 95 # a = ‘tanglaoer‘ 96 # b = a.index(‘a‘) 97 # c = a.index(‘p‘) 98 # print(b) # 1 99 # print(c) # 报错 100 101 """ 102 find() & index() 的比较 103 1. 用find() 找不到不会报错 104 """ 105 106 # isalnum() 字符串中是否只包含 字母（包括汉字）和数字 107 a = ‘tang8080唐‘ 108 b = ‘tang8080_‘ 109 c = a.isalnum() 110 d = b.isalnum() 111 print(c) # True 112 print(d) # False 113 114 # isalpha() 字符串是否只包含字母 汉字 115 a = "tanglaoer" 116 b = ‘唐‘ 117 c = a.isalpha() 118 d = b.isalpha() 119 print(c) # True 120 print(d) # True 121 122 # isdigest() isdecimal() 判断是否是数字 123 a = "123" 124 b = "②" 125 t = ‘二‘ 126 c = a.isdecimal() # 只可以识别 这种"123" 用来判断计算就用这种 127 d = a.isdigit() 128 e = b.isdecimal() 129 f = b.isdigit() 130 g = t.isnumeric() # 可以识别中文数字 131 print(c,d,e,f,g) # True True False True True 132 """ 133 isdigit() & isdecimal() 比较 134 1. 用isdigit() 范围更广 135 """ 136 137 # swapcase() 大小写转换 138 a = ‘TangLaoEr‘ 139 b = a.swapcase() 140 print(b) # tANGlAOeR 141 142 # isidentifier() 判断是否是标识符 143 # 数字 字母 下划线 and 字母 下划线 开头 144 145 146 # isprintable() 判断是否存在不可显示字符 ，注意：空格是可显示的 147 a = "tang lao" 148 b = a.isprintable() 149 print(b) # False 150 151 # isspace() 判断是否全部是空格， 都满足 152 a = "tanglaoer" 153 b = " " 154 t = " " 155 p = " " 156 c = a.isspace() 157 d = b.isspace() 158 g = t.isspace() 159 pp = p.isspace() 160 print(c,d,g,pp) # False True True True 161 162 # istitle() 判断是否是标题 每个单词首字母大写 163 a = ‘tang lao er‘ 164 b = a.istitle() 165 c = a.title() 166 print(b)# False 167 print(c)# Tang Lao Er 168 169 # 这个很重要 170 # join() 拼接字符串 每一个元素按照指定分隔符进行拼接 171 a = "tanglaoer" 172 c = ‘飞流直下三千尺‘ 173 print(a) 174 b = " ".join(a) 175 d = "_".join(c) 176 print(b) # t a n g l a o e r 177 print(d) # 飞_流_直_下_三_千_尺 178 179 # ljust() rjust() 指定宽度，字符串放一边 剩下的填充 180 # ljust(self, width, fillchar=None) 181 # rjust(self, width, fillchar=None) 182 a = ‘tang‘ 183 b = a.ljust(20,‘*‘) 184 c = a.rjust(20,‘*‘) 185 print(b) # tang**************** 186 print(c) # ****************tang 187 188 # zfill() 以0来填充 189 a = "tang" 190 b = a.zfill(20) 191 print(b) # 0000000000000000tang 192 193 # islower() 判断是否是小写 194 a = ‘Tang‘ 195 b = a.islower() 196 print(b) # False 197 198 # isupper() 判断是否是大写 199 a = ‘Tang‘ 200 b = a.isupper() 201 print(b) # False 202 203 # upper() 转换为大写 204 a = ‘Tang‘ 205 b = a.upper() 206 print(b) # TANG 207 208 # 移除指定字符串 209 #strip() 默认去除空格 ,可以指定匹配的子序列 210 # strip(self, chars=None) 211 a = " tang " 212 b = a.lstrip() 213 c = a.rstrip() 214 d = a.strip() 215 print(b)#tang 216 print(c)# tang 217 print(d)#tang 218 219 # 注意：是子序列里面的都可以匹配掉 220 a = ‘axtangxa‘ 221 b = a.lstrip(‘ax‘) 222 c = a.rstrip(‘ax‘) 223 d = a.strip(‘ax‘) 224 print(b)#tangxa 225 print(c)#axtang 226 print(d)#tang 227 228 # maketrans() translate() 自定义替换,两个函数配套使用 229 st = "ajketjaeoijmdgajtyopayjhpaeg" 230 a = str.maketrans("aeiou","12345") # a=1,e=2,i=3,o=4,u=5 231 at = st.translate(a) 232 print(at) # 1jk2tj1243jmdg1jty4p1yjhp12g 233 234 # partition() 分割,分成三部分成元组，可以拿到sep 235 # partition(self, sep) 236 a = ‘tanglaoer‘ 237 b = a.partition(‘a‘) 238 c = a.partition(‘ao‘) 239 d = a.partition(‘r‘) 240 print(b) # (‘t‘, ‘a‘, ‘nglaoer‘) 241 print(c) # (‘tangl‘, ‘ao‘, ‘er‘) 242 print(d) # (‘tanglaoe‘, ‘r‘, ‘‘) 243 244 # split() lsplit() rsplit() # 分割,按sep分割成列表，不可以拿到sep 245 # split(self, sep=None, maxsplit=-1) maxsplit=分割次数 246 a = ‘tanglaoer‘ 247 b = a.split(‘a‘) 248 c = a.rsplit(‘a‘,1) 249 print(b) # [‘t‘, ‘ngl‘, ‘oer‘] 250 print(c) # [‘tangl‘, ‘oer‘] 251 252 # splitlines() 分割 253 # splitlines(self, keepends=None) keepends=True | False 254 a = "aldgjal ajlkgjal algladjg" 255 b = a.splitlines(False) 256 c = a.splitlines(True) 257 print(b) # [‘aldgjal‘, ‘ajlkgjal‘, ‘algladjg‘] 258 print(c) # [‘aldgjal ‘, ‘ajlkgjal ‘, ‘algladjg‘] 259 260 # startswith() 以什么开头 261 # startswith(self, prefix, start=None, end=None) 262 a = "tanglaoer" 263 b = a.startswith(‘a‘) 264 c = a.startswith(‘a‘,1) 265 print(b) # False 266 print(c) # True 267 268 # replace() 替换 269 # replace(self, old, new, count=None) count=替换的次数 270 a = "tanglaoer" 271 b = a.replace("a","T") 272 c = a.replace("a","T",1) 273 print(b) #tTnglToer 274 print(c) #tTnglaoer 275 276 # ******************************以下必须知道的*************** 277 # 获取字符串中的某一个 278 # 通过索引，下标 279 a = ‘tanglaoer‘ 280 b = a[2] 281 print(b) # n 282 283 # 通过[M:n]切片 -1:表示最后一个 284 a = ‘tanglaoer‘ 285 b = a[0:1] #[0,1) 286 c = a[0:-1] #[0,-1) 287 print(b) # t 288 print(c) # tanglaoe 289 290 # len() 求长度 291 a = ‘tanglaoer‘ 292 c = ‘唐老二‘ 293 b = len(a) 294 d = len(c) 295 print(b) # 9 296 print(d) # 3 注意: 在python2中拿到的是9 297 298 # for 循环取值 299 a = ‘tanglaoer‘ 300 for i in a: 301 print(i,end=‘ ‘) #t a n g l a o e r 302 print() 303 304 # 字符串拼接 305 """ 306 内存理解： 字符串是不可变类型 307 1.首先a申请一块内存存放"tanglaoer" 308 2.b申请一块内存存放"18" 309 3.c重新申请一块内存放"tanglaoer18" 310 """ 311 a = "tanglaoer" 312 b = "18" 313 c = a + b 314 print(c) # tanglaoer18
布尔值 bool
a = bool(12) print(a) # True a = True print(a) # True a = False print(a) # False # 为False的值 # "" () [] {} 0 None
列表 list
__author__ = "Tang" # 列表中的元素 数字，字符串，列表，布尔值... li = [1, ‘age‘, [‘tang‘, [‘lao‘, ‘er‘]], True] # 索引取值 print(li[1]) # age print(li[2][0]) # tang # 切片 取值 print(li[2:-1]) # [[‘tang‘, [‘lao‘, ‘er‘]]] # for循环 while 循环 取值 # for item in li: # print(item) # 列表元素，可以被修改 是可变类型 li = [1, ‘age‘, [‘tang‘, [‘lao‘, ‘er‘]], True] # 索引修改 li[0] = 20 print(li[0]) # 删除 del li[1] print(li) # [20, [‘tang‘, [‘lao‘, ‘er‘]], True] # 切片 修改多个值 li = [1, 12, 9, ‘age‘, [‘tang‘, [‘lao‘, ‘er‘]], True] li[1:3] = [120, 90] print(li) # [1, 120, 90, ‘age‘, [‘tang‘, [‘lao‘, ‘er‘]], True] # 切片 删除多个值 li = [1, 12, 9, ‘age‘, [‘tang‘, [‘lao‘, ‘er‘]], True] del li[2:6] print(li) # [1, 12] # in 操作 li = [1, 12, 9, ‘age‘, [‘tang‘, [‘lao‘, ‘er‘]], True] v = "age" in li print(v) # True v = ‘tang‘ in li print(v) # False v = [‘tang‘, [‘lao‘, ‘er‘]] in li print(v) # True # 取值操作 li = [1, 12, 9, ‘age‘, [‘tang‘, [‘lao‘, ‘er‘]], True] print(li[3][1]) # g print(li[4][1][0]) # lao # 数字 字符串转换 a = "123" s = int(a) print(s, type(s)) # 123 <class ‘int‘> a = 123 s = str(a) print(s, type(s)) # 123 <class ‘str‘> # 字符串转换成列表 s = "tanglaoer" new_li = list(s) # 内部使用for循环 print(new_li) # [‘t‘, ‘a‘, ‘n‘, ‘g‘, ‘l‘, ‘a‘, ‘o‘, ‘e‘, ‘r‘] # 列表转换成字符串 li = [11, 22, 33, "123", "tang", True] r = str(li) print(r) # [11, 22, 33, ‘123‘, ‘tang‘, True] # 列表转换成字符串 第一种 失败 li = [11, 22, 33, "123", "tang", True] s = "" li = str(li) # 每一个字符是一个元素 11就代表两个元素 包括[]号也是元素 for i in li: print(i) """ [ 1 1 , 2 2 , 3 3 , ‘ 1 2 3 ‘ , ‘ t a n g ‘ , T r u e ] """ s += i print(s) # [11, 22, 33, ‘123‘, ‘tang‘, True] # 列表转换成字符串 第二种 有点麻烦 li = [11, 22, 33, "123", "tang", True] s = "" for i in li: s = s + str(i) print(s) # 112233123tangTrue # 列表转换成字符串 第三种 完美 li = [11, 22, 33, "123", "tang", True] # 因为列表里面有整型 不能直接转换为字符串 # s = "".join(li) # 报错 TypeError: sequence item 0: expected str instance, int found s = "".join(‘%s‘ % i for i in li) print(s) # 112233123tangTrue # 这个很重要 列表 元组 字符串 使用切片【M:N】取值 超出边界不报错 # 如果是根据【n】索引取值，就会报错 # li = [1,2,3,4,5,6,7] # tt = li[10:] # print(tt) # [] # print(tt[10]) # 报错 # st = "tanglaoer" # st2 = st[10:] # st3 = st[1:] # print(st2) # 空格 # print(st3) # anglaoer # print(st[20]) 报错 # tup = (1,2,3,4,5,) # tup2 = tup[10:] # tup3 = tup[10] # print(tup2) # 空格 # print(tup3) # 报错 ##############list 方法################# # append() 追加 li = [11, 22, 33, 44] v = li.append(55) print(v) # None print(li) # [11, 22, 33, 44, 55] # clear() 清空 li = [11, 22, 33, 44] v = li.clear() print(v) # None print(li) # [] # copy() 浅拷贝 li = [11, 22, 33, 44] v = li.copy() print(v) # [11, 22, 33, 44] print(li) # [11, 22, 33, 44] # count() 统计 li = [11, 22, 33, 44] v = li.count(22) print(v) # 1 print(li) # [11, 22, 33, 44] # extend() 扩展 # extend(self, iterable) iterable=可迭代对象(字符串 列表 元组） li = [11, 22, 33, 44] v = li.extend([‘a‘, ‘b‘, ‘c‘, 90, 50, ‘tang‘]) v2 = li.extend(‘tanglaoer‘) print(v) # None print(li) # [11, 22, 33, 44, ‘a‘, ‘b‘, ‘c‘, 90, 50, ‘tang‘, ‘t‘, ‘a‘, ‘n‘, ‘g‘, ‘l‘, ‘a‘, ‘o‘, ‘e‘, ‘r‘] print(v2) # None """ append() & extend() 的区别: 1. append() 参数如果是可迭代对象，不会循环取值，而是当做整体插入 2. extend() 循环取值，一个一个的插入 """ # index() 寻找索引 # index(self, value, start=None, stop=None) li = [11, 22, 33, 22, 44] v = li.index(22) v2 = li.index(22, 2) print(v) # 1 print(v2) # 3 # insert() 在指定位置插入值 # insert(self, index, p_object) li = [11, 22, 33, 44] v = li.insert(3, 22) print(v) # None print(li) # [11, 22, 33, 22, 44] # pop() 删除某索引并返回其位置的值 默认删除最后一个 # pop(self, index=None) li = [11, 22, 33, 44] v = li.pop(2) v2 = li.pop() print(v) # 33 print(v2) # 44 print(li) # [11, 22] # remove() 删除某一个值 # remove(self, value) 左边优先 li = [11, 22, 33, 44] v = li.remove(22) print(v) # None print(li) # [11, 33, 44] # del() 删除 li = [11, 22, 33, 44] del li[0] print(li) # [22, 33, 44] del li[0:1] print(li) # [33, 44] """ pop() & remove() & clear() & del 1. pop() 参数为索引下标 2. remove() 参数为值 3. clear() 清空所有 4. del 删除某指定的位置，也可以切片 """ # reverse() 将当前列表进行反转 li = [11, 22, 33, 44] v = li.reverse() print(v) # None print(li) # [44, 33, 22, 11] # sort() 排序 # sort(self, key=None, reverse=False) 默认从小到大排序 li = [11, 22, 33, 44] v = li.sort() print(v) # None print(li) # [11, 22, 33, 44] v2 = li.sort(reverse=True) # 从大到小排序 print(v2) # None print(li) # [44, 33, 22, 11] # 查看地址 li = [11, 22, 33, 44] print(li ,id(li)) # [11, 22, 33, 44] 50110832 li.append(55) print(li,id(li)) # [11, 22, 33, 44, 55] 50110832 # 列表是可变类型 li = [11, 22, 33, 44] print(li[0]) # 11 li[0] = 99 print(li[0]) # 99 # 字符串是不可变类型 s = "tanglaoer" s[0] = ‘B‘ print(s[0]) # 报错
元组 tuple
__author__ = "Tang" # 元组 元素不可被修改 tu = (111, 22, 33, 44,) # tu[0] = 999 # 报错 # del tu[0] # 报错 print(tu) # (111, 22, 33, 44) # 在最后多加一个逗号 区别于方法 整型 不加也不报错 l = (11) print(l) # 11 整型 l2 = (11,) print(l2) # (11,) 元组 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) print(tu) # (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) # 索引取值 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) v = tu[0] print(v) # 111 # 切片取值 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) v = tu[0:3] print(v) # (111, ‘tang‘, (1, 2, 3)) # 循环取值 是可迭代对象 # tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) # for i in tu: # print(i) """ 111 tang (1, 2, 3) [4, 5, 6] True 45 """ # 元组转列表 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) tu = list(tu) print(tu) # [111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45] # 列表转元组 li = [111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45] tu = tuple(li) print(tu) # (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) # 字符串转元组 s = "tanglaoer" tu = tuple(s) print(tu) # (‘t‘, ‘a‘, ‘n‘, ‘g‘, ‘l‘, ‘a‘, ‘o‘, ‘e‘, ‘r‘) # 元组转字符串第一种 元组不仅仅是字符串 只能自己写for循环 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) v = "".join("%s"%str(i) for i in tu) print(v,type(v)) # 111tang(1, 2, 3)[4, 5, 6]True45 <class ‘str‘> # 元组转字符串第二种 元组都是字符串 tu = (‘tang‘,‘lao‘,‘er‘,) v = "".join(tu) print(v) # tanglaoer # 元组 列表都是有序的 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6], True, 45) v = tu[2][2] print(v) # 3 # 元组里面的一级元素不可以修改/删除/增加 二级元素可以修改 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6,(33,44)], True, 45) print(tu[3][0]) # 4 tu[3][0] = 14 print(tu[3][0]) # 14 print(tu[3][3]) # (33, 44) tu[3][3] = 8989 print(tu[3][3]) # 8989 ##########################tuple 方法########## # count() 获取指定元素的个数 tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6,(33,44)], True, 45, 45,65,45) v = tu.count(45) print(v) # 3 # index() 获取指定元素的索引下标 # index(self, value, start=None, stop=None) tu = (111, ‘tang‘, (1, 2, 3), [4, 5, 6,(33,44)], True, 45, 45,65,45) v = tu.index(45) print(v) # 5
字典 dict
__author__ = "Tang" # 键值对 dict a = { ‘a‘: 1, ‘b‘: 2, ‘c‘: 3 } print(a) # {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} info = { "key0": True, "key1": 10, "key2": 20, "key3": 30, "key4": [11, 22, 33], "key5": (44, 55, 66,), "key6": {‘k0‘: ‘v0‘, ‘k1‘: ‘v1‘, ‘k2‘: ‘v2‘} } print(info) """ {‘key0‘: True, ‘key1‘: 10, ‘key2‘: 20, ‘key3‘: 30, ‘key4‘: [11, 22, 33], ‘key5‘: (44, 55, 66), ‘key6‘: {‘k0‘: ‘v0‘, ‘k1‘: ‘v1‘, ‘k2‘: ‘v2‘}} """ # 通过上面例子可以知道 value 可以是任意类型 # 字典的key 可以是整型 字符串 元组 布尔 而列表跟字典可变数据类型不可以当key tt = { 2: ‘1‘, ‘st‘: ‘st‘, True: "123", (11, 22,): (11, 22) } print(tt) # {2: ‘1‘, ‘st‘: ‘st‘, True: ‘123‘, (11, 22): (11, 22)} # 字典是无序的 不可以通过索引取值 切片 # dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} # print(dt[1]) # 报错 # 通过key取值 dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} print(dt[‘a‘]) # 1 # 删除 dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} del dt[‘a‘] print(dt) # {‘b‘: 2, ‘c‘: 3} # 循环取值 info = { "key0": True, "key1": 10, "key2": 20, "key3": 30, "key4": [11, 22, 33], "key5": (44, 55, 66,), "key6": {‘k0‘: ‘v0‘, ‘k1‘: ‘v1‘, ‘k2‘: ‘v2‘} } for item in info: # 默认是取键 print(item) """ key0 key1 key2 key3 key4 key5 key6 """ for item in info.keys(): # 取键 print(item) for item in info.values(): # 取值 print(item) for k, v in info.items(): # 取键 & 值 print(k, v) # 字典的键要唯一 如果重复只显示第一个 注意：True=1 False=0 test = {1: ‘1‘, True: ‘1‘} print(test) # {1: ‘1‘} test = {2: ‘1‘, True: ‘1‘} print(test) # {2: ‘1‘, True: ‘1‘} ################# dict 的方法 # fromkeys() 类的静态方法 # fromkeys(*args, **kwargs) v = dict.fromkeys([11, 22, 33]) print(v) # {11: None, 22: None, 33: None} v = dict.fromkeys([11, 22, 33], [‘a‘, ‘b‘]) print(v) # {11: [‘a‘, ‘b‘], 22: [‘a‘, ‘b‘], 33: [‘a‘, ‘b‘]} # 通过索引取值，如果键不存在就报错 # 用get函数取值，不存在不报错，并且可以指定默认值 # get() 取值 dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} v = dt.get(‘a‘,99) print(v) # 1 v = dt.get(‘z‘,99) # 如果不存在，取第二个参数的值 print(v) # 99 # pop() 删除 dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} v = dt.pop(‘a‘,99) print(v) # 1 v = dt.pop(‘z‘,99) # 键不存在 得到默认值 print(v) # 99 # popitem() 随机删除一个 dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} v = dt.popitem() # 删除并返回一个元组 print(v) # (‘c‘, 3) k,v = dt.popitem() print(k,v) # b 2 # setdefault() 键已经存在，不设置并获取已存在的值，键不存在，就设置并取当前设置的值 dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} v = dt.setdefault(‘a‘,‘10‘) print(v) # 1 print(dt) # {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} v = dt.setdefault(‘z‘,‘10‘) print(v) # 10 print(dt) # {‘a‘: 1, ‘b‘: 2, ‘c‘: 3, ‘z‘: ‘10‘} # update() 更新 dt = {‘a‘: 1, ‘b‘: 2, ‘c‘: 3} dt.update({‘a‘:‘10‘,‘z‘:‘100‘}) print(dt) # {‘a‘: ‘10‘, ‘b‘: 2, ‘c‘: 3, ‘z‘: ‘100‘} dt.update(k=123,k2=456,k3="789") print(dt) # {‘a‘: ‘10‘, ‘b‘: 2, ‘c‘: 3, ‘z‘: ‘100‘, ‘k‘: 123, ‘k2‘: 456, ‘k3‘: ‘789‘} """ 必会： keys() values() get() update() items() """
整理常用的
__author__ = "Tang" """常用的""" # 整型 # int() # 字符串 # replace/find/join/strip/startswith/split/upper/lower/format tempate = "my name is {name},hobby is {hobby}" v = tempate.format(name=‘tang‘,hobby=‘游戏‘) print(v) # my name is tang,hobby is 游戏 v = tempate.format(**{‘name‘:‘tang‘,‘hobby‘:‘游戏‘}) print(v) # my name is tang,hobby is 游戏 # 列表 # append/extend/insert # 索引、切片、循环 取值 # 元组 # count/index # 字典 # get/update/keys/values/items/fromkeys
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