基础数据类型补充,及capy daty7
1,基础数据类型,总结补充.
int:bit_lenth() str: captilze() 首字母大写,其余小写. upper() 全大写. lower() 全小写. find() 通过元素找索引,没有返回-1,有切片. index() 通过元素找索引,没有回报错.有切片 swapcase() 大小写反转. strip() 去除前后端的空格,\n,\t, strip('abc') 去除前后端的a ,b,c三个元素, ltrip ,rtrip title 非字母隔开的部分,首字母大写 split str---> list 默认以空格(可以设定分隔符), startswith 判断s以什么开头,返回bool值,可以切片 endswith 判断以什么结尾,返回bool值,可以切片 replace(old,new) 默认不写次数,全体换 center 以其为中心,默认填充物 空格. count 计算元素出现的次数. len() 测量字符串的长度. join '' '*' '_'.... .join(interable) isalpha() 全都是字母组成 isdigit() 全都是数字组成 isalnum() 全都是字母或者数字 '%s' %(name) name1 = 'taibai ' '%(name)s' %{name:name1} format '{}{}{}'.format(name,age,hobby) '{0}{1}{2}{1}'.format(name,age,bobby) '{name},{age}'.format(age=12,name='太白')
int数字
str字符串
s = ' ' #只能是以至少一个空格组成的字符串(全空格) print(s.isspace())
tuple元祖
tu = (1) tu1 = (1,) print(tu,type(tu)) print(tu1,type(tu1)) tu = ('alex') tu1 = ('alex',) print(tu,type(tu)) print(tu1,type(tu1)) tu = ([1,2,3]) tu1 = ([1,2,3],) print(tu,type(tu)) print(tu1,type(tu1)) 当元组只有一个元素组成并且没有',' 则该元素是什么数据类型,整体就是什么数据类型. tu.append('333') print(tu)
list
l1 = [111,222,333,444,555] for i in range(len(l1)): # i = 0 i = 1 i = 2 i = 3 print(l1) del l1[i] print(l1) # [222,333,444,555] [222,444,555] [222,444] print(l1) l1 = [111,222,333,444,555] 将索引为奇数位的元素删除. l1.pop(222) l1.remove(1) 方法一: l1 = [111,222,333,444,555] l2 = [] for i in range(len(l1)): if i % 2 == 0: l2.append(l1[i]) l1 = l2 print(l1) 方法二: l1 = [111,222,333,444,555] for i in range(1,len(l1)): if i <= 2 : l1.pop(i) print(l1) 方法二: l1 = [111,222,333,444,555,666,777] # del l1[1::2] print(l1) l1 = [111,222,333,444,555] for i in range(len(l1)-1,0,-1): if i % 2 == 1: del l1[i] print(l1) 在循环一个列表时,如果要是删除某些或者某类元素,容易出错. fromkeys() dic = dict.fromkeys('abc','alex') print(dic) dic1 = dict.fromkeys([1,2,3],[]) print(dic1) dic1[1].append('alex') print(dic1) dic = {'k1':'alex','k2':'太白','k3':'日天','name':'wusir'} 不可变的数据类型:可哈希 for i in dic: if 'k' in i: del dic[i] l1 = [] for i in dic: if 'k' in i: l1.append(i) print(l1) for k in l1: del dic[k] print(dic) 在循环一个字典时,如果删除某些键值对,可能会报错. 数据类型之间的转化: int <---> str int <---> bool str <--->.bool split str <------> list join tuple <---> list l1 = [1,2,3] tu = tuple(l1) l2 = list(tu) print(tu,l2) dict专属类型:与list转换 dic = {'k1':'alex','k2':'太白','k3':'日天','name':'wusir'} print(list(dic.keys())) print(list(dic.values())) print(list(dic.items()))
2,深浅copy.
l1 = [1,2,3,4] l2 = l1 l1.append(5) print(l1,l2) 对于赋值运算,就是共同指向一个内存地址. s1 = 'alex' s2 = s1 s1 = 'alex2' print(s1,id(s1)) print(s2,id(s2)) copy l1 = [1,2,3] l2 = l1.copy() l1.append(666) print(l1,id(l1)) print(l2,id(l2)) l1 = [1,[22,33],2,3] l2 = l1.copy() l1.append(666) print(l1,id(l1)) print(l2,id(l2)) l1 = [1,[22,33,],2,3] l2 = l1.copy() l1[1].append(666) print(l1,id(l1),id(l1[1])) print(l2,id(l2),id(l2[1])) 对于浅copy来说,第一层都是独立的内存地址,从第二层开始,都是指向同一个内存地址,一变都变. import copy l1 = [1,[22,33,],2,3] l2 = copy.deepcopy(l1) l1.append(777) l1[1].append(666) print(l1,id(l1),id(l1[1])) print(l2,id(l2),id(l2[1])) 对于深copy,无论多少层,在内存中都是两个独立的内存地址. l1 = [1,[1,2],2,3] l2 = l1[:] # 是浅copy l1[1].append(111) print(l1,l2) l2 是什么?