【Python操作基础】系列——列表操作，建议收藏！
该篇文章首先利用Python展示了使用列表类型数据的相关操作，包括基本用法；切片操作；反向遍历；类型转换；extend和append的区别；列表推导式；删除和插入；常用操作函数等。
1 基本用法
运行程序：
myList1 = [21,22,23,24,25,26,27,28,29] myList1
myList2=myList1 myList2
myList3=list(“Data”) myList3
myList1[-1] #倒数第几个
myList1[-9]
#myList1[9] #报错：超过边界
2 切片操作
运行程序：
myList1 = [21,22,23,24,25,26,27,28,29] myList1 myList1[1:8] #第2个到第个 myList1[1:8:2] #步长为2 myList1[:5] #第1个到第5个 myList1[:] #所有 myList1[2:] #第3个到最后 myList1[:-1] #第1个到倒数第2个
运行结果：
[21, 22, 23, 24, 25, 26, 27, 28, 29] [22, 23, 24, 25, 26, 27, 28] [22, 24, 26, 28] [21, 22, 23, 24, 25] [21, 22, 23, 24, 25, 26, 27, 28, 29] [23, 24, 25, 26, 27, 28, 29] 29
3 反向遍历
运行程序：
myList1 = [21,22,23,24,25,26,27,28,29] myList1 myList1[::-1] #倒序 myList1 myList1[:-1] reversed(myList1) #返回值为一个迭代器 list(reversed(myList1)) #list强制转换显示内容 myList1 myList1.reverse()#内置函数不改变列表本身 myList1
运行结果：
[21, 22, 23, 24, 25, 26, 27, 28, 29] [29, 28, 27, 26, 25, 24, 23, 22, 21] [21, 22, 23, 24, 25, 26, 27, 28, 29] [21, 22, 23, 24, 25, 26, 27, 28] <list_reverseiterator at 0x26c0cdc18d0> [29, 28, 27, 26, 25, 24, 23, 22, 21] [21, 22, 23, 24, 25, 26, 27, 28, 29] [29, 28, 27, 26, 25, 24, 23, 22, 21]
4 类型转换
运行程序：
list("chaolemen")
运行结果：
['c', 'h', 'a', 'o', 'l', 'e', 'm', 'e', 'n']
5 extend与append的区别
运行程序：
from IPython.core.interactiveshell import InteractiveShell InteractiveShell.ast_node_interactivity = "all" ##执行多输出 myList1 = [21,22,23,24,25,26,27,28,29] myList2=myList1 myList1 + myList2 myList1 = [21,22,23,24,25,26,27,28,29] myList2=myList1 myList1.extend(myList2) #列表1上后面加列表2，以成员身份追加 myList1 myList1.append(myList2)#平等追加 myList1 myList1 = [1,2,3,4,5,6,7,8,9] myList3 = [11,12,13,14,15,16,17,18,19] [i + j for i, j in zip(myList1, myList3)] #两个列表数值相加
运行结果：
[21, 22, 23, 24, 25, 26, 27, 28, 29, 21, 22, 23, 24, 25, 26, 27, 28, 29] [21, 22, 23, 24, 25, 26, 27, 28, 29, 21, 22, 23, 24, 25, 26, 27, 28, 29] [21, 22, 23, 24, 25, 26, 27, 28, 29, 21, 22, 23, 24, 25, 26, 27, 28, 29, [...]] [12, 14, 16, 18, 20, 22, 24, 26, 28]
6 列表推导式
运行程序：
[2 for i in range(20)] [i for i in range(1, 21)] [i for i in range(1, 21, 2)] range(10) list(range(0,10,2)) [type(item) for item in [True,"1",1,1.0]] print([ord(i) for i in ['朝', '乐', '门']]) ["input/%d.txt" % i + "dd%d" % i for i in range(5)]#可以用字符串的占位符 ["input/%d.txt"%i + "_%d" %i for i in range(5)]
运行结果：
[2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2] [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] [1, 3, 5, 7, 9, 11, 13, 15, 17, 19] range(0, 10) [0, 2, 4, 6, 8] [bool, str, int, float] [26397, 20048, 38376] ['input/0.txtdd0', 'input/1.txtdd1', 'input/2.txtdd2', 'input/3.txtdd3', 'input/4.txtdd4'] ['input/0.txt_0', 'input/1.txt_1', 'input/2.txt_2', 'input/3.txt_3', 'input/4.txt_4']
7 删除与插入
运行程序：
lst_1 = [10,10,11,12,13,14,15] lst_1.insert(1, 8) #插入insert(插入下标位置, 插入值) lst_1 lst_1 = [10,10,11,12,13,14,15] lst_1.pop(2) #删除列表下标为2的值 lst_1 lst_1 = [10,10,11,12,13,14,15] del lst_1[2] #下标删除 lst_1 lst_1 = [10,10,11,12,13,14,15] lst_1.remove(10) #只删除第一个10 lst_1 lst_1 = [10,10,11,12,11,13,14,15] for i in lst_1 : if i == 11: lst_1.remove(i) #删除11 print(lst_1) lst_1 = [10,10,11,12,11,13,14,15] [x for x in lst_1 if x != 10] #删除所有10 lst_1 = [10,10,11,12,11,13,14,15] list(filter(lambda i:i!=10, lst_1)) #过滤10 lst_1 = [10,10,11,12,11,13,14,15] list(set(lst_1))#过滤重复值
运行结果：
[10, 8, 10, 11, 12, 13, 14, 15] 11 [10, 10, 12, 13, 14, 15] [10, 10, 12, 13, 14, 15] [10, 11, 12, 13, 14, 15] [10, 10, 12, 13, 14, 15] [11, 12, 11, 13, 14, 15] [11, 12, 11, 13, 14, 15] [10, 11, 12, 13, 14, 15]
8 常用操作函数
运行程序：
lst_1 = [10,10,11,12,13,14,15] len(lst_1) #列表长度 lst_1 = [10,10,11,12,11,13,14,15] sorted(lst_1) #列表排序，正序，不改变原序列 lst_1 lst_1 = [10,10,11,12,11,13,14,15] lst_1.sort() #列表排序，正序，改变原序列 lst_1 lst_1 = [10,10,11,12,11,13,14,15] lst_2=[11,12,13,14] #1列表后加2列表，加一整个列表 lst_1.append(lst_2) print(lst_1) lst_1 = [10,10,11,12,11,13,14,15] lst_2=[11,12,13,14] lst_1.extend(lst_2) # #1列表后加2列表，直接原列表后面加 print(lst_1) lst_1 = [1,2,3,'Python',True,4.3,None] lst_2 = [1,2,[2,3]] print(lst_1, lst_2) #依次输出两个列表 lst_1 = [1,2,3,'Python',True,4.3,None] list(reversed(lst_1)) #倒序列表 reversed(lst_1) #倒序列表，输出格式 lst_1 [1, 2, 3, 'Python', True, 4.3, None] lst_1 = [1,2,3,'Python',True,4.3,None] lst_1.reverse()#倒序列表 lst_1 str1=[1,2,3,4,5] str2=[20,21,23,24,25] print(zip(str1,str2))#两列表同步运算，输出格式 print(list(zip(str1,str2))) #强制转化为值 str1=["a","about","c","china","b","beijing"] [x.upper() for x in str1 if len(x)>1] #输出列表中长度大于1的字符串 [x**2 for x in range(10)] #列表运算 str1=["a","about","c","china","b","beijing"] [str2.upper() for str2 in str1 if len(str2)>1]#输出列表1中长度大于1的字符串 myList=[2,3,5,6,7,3,2] list(enumerate(myList))#内置函数 i=0 sum=0 for value in myList: i=i+1 sum=value+i sum sum=0 [dict((value,i) for i, value in enumerate(myList))]
运行结果：
7 [10, 10, 11, 11, 12, 13, 14, 15] [10, 10, 11, 12, 11, 13, 14, 15] [10, 10, 11, 11, 12, 13, 14, 15] [10, 10, 11, 12, 11, 13, 14, 15, [11, 12, 13, 14]] [10, 10, 11, 12, 11, 13, 14, 15, 11, 12, 13, 14] [1, 2, 3, 'Python', True, 4.3, None] [1, 2, [2, 3]] [None, 4.3, True, 'Python', 3, 2, 1] <list_reverseiterator at 0x2cd44ac2f28> [1, 2, 3, 'Python', True, 4.3, None] [1, 2, 3, 'Python', True, 4.3, None] [None, 4.3, True, 'Python', 3, 2, 1] <zip object at 0x000002CD42AA2E48> [(1, 20), (2, 21), (3, 23), (4, 24), (5, 25)] ['ABOUT', 'CHINA', 'BEIJING'] [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] ['ABOUT', 'CHINA', 'BEIJING'] [(0, 2), (1, 3), (2, 5), (3, 6), (4, 7), (5, 3), (6, 2)] 9 [{2: 6, 3: 5, 5: 2, 6: 3, 7: 4}]
