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  • python 列表操作

    列表生成式:

    a=[x*x for x in range(10)]#等价[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]


    索引(下标) ,都是从0开始
    切片
    .count 查某个元素的出现次数
    .index 根据内容找其对应的位置
    "x" in a
    增加
    a.append() 追加
    a.insert(index, "内容")
    a.extend 扩展

    修改
    a[index] = "新的值"
    a[start:end] = [a,b,c]

    删除
    remove("内容")
    pop(index)
    del a, del a[index]
    a.clear() 清空

    排序
    sort ()
    reverse()

    身份判断
    >>> type(a) is list
    True

    切片:

    a=['0','1','2','3','4','5','6']
    
    print(1,a[:]) #all
    print(2,a[0:])
    print(3,a[0:-1])#最后一个不取
    print(4,a[0:7])#和range类似
    print(5,a[0:6:2])
    print(6,a[0::2])
    print(7,a[::-1])#逆置
    print(8,a[6::-1])
    print(9,a[6::-2])
    print(10,a[:0:-2])#取不到0
    print(11,a[-1::-2])
    1 ['0', '1', '2', '3', '4', '5', '6']
    2 ['0', '1', '2', '3', '4', '5', '6']
    3 ['0', '1', '2', '3', '4', '5']
    4 ['0', '1', '2', '3', '4', '5', '6']
    5 ['0', '2', '4']
    6 ['0', '2', '4', '6']
    7 ['6', '5', '4', '3', '2', '1', '0']
    8 ['6', '5', '4', '3', '2', '1', '0']
    9 ['6', '4', '2', '0']
    10 ['6', '4', '2']
    11 ['6', '4', '2', '0']

    增加:(append、insert)

    a=['0','1']
    a.append(2)
    print(a)
    a.insert(1,"123")
    print(a)
    ['0', '1', 2]
    ['0', '123', '1', 2]

    修改:

    a=['0','1','2']
    a[1]=2
    print(a)
    a[0:2]=['a','b']
    print(a)
    ['0', 2, '2']
    ['a', 'b', '2']

    删除:(remove、pop、del)

    a=['0','1','2','1','3']
    a.remove('1')
    print(a)
    b=a.pop(1)
    print(b)
    print(a)
    del a[0]
    print(a)
    a.clear()#清空列表
    ['0', '2', '1', '3']
    2
    ['0', '1', '3']
    ['1', '3']

     

    列表内置的important方法:

    a=['0','1','2','1','3']
    b=['1','2','3']
    print(a.count('1'))#计算元素出现次数
    print(a.index('1'))#找到特定元素的位置
    
    a.extend(b) #把b中元素添加到a中元素
    print(a)
    
    a.reverse() # 逆置
    print(a)
    
    a.sort() #排序
    print(a)
    2
    1
    ['0', '1', '2', '1', '3', '1', '2', '3']
    ['3', '2', '1', '3', '1', '2', '1', '0']
    ['0', '1', '1', '1', '2', '2', '3', '3']
    

     

    随便用
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  • 原文地址:https://www.cnblogs.com/pqhuang/p/11193762.html
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