一. 課上代碼

#刪除元素的三種方法
>>> member = ['fish', 'Jack', 'dark', 'David', 'road', 'quiet', 'sun']
>>> member
['fish', 'Jack', 'dark', 'David', 'road', 'quiet', 'sun']
>>> member.remove('David')
>>> member
['fish', 'Jack', 'dark', 'road', 'quiet', 'sun']
>>> member.remove('HsinChi')
Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    member.remove('HsinChi')
ValueError: list.remove(x): x not in list
#remove()的話必須得知道數(shù)組中有哪個(gè)具體元素然后再進(jìn)行刪除

>>> del member[1]
>>> member
['fish', 'dark', 'road', 'quiet', 'sun']
>>> del member
>>> member
Traceback (most recent call last):
  File "<pyshell#9>", line 1, in <module>
    member
NameError: name 'member' is not defined
#del 可以將整個(gè)數(shù)組刪除，或者刪除特定位置的元素

>>> member = ['fish', 'Jack', 'dark', 'David', 'road', 'quiet', 'sun']
>>> member.pop()
'sun'
>>> member
['fish', 'Jack', 'dark', 'David', 'road', 'quiet']
>>> name = member.pop()
>>> name
'quiet'
>>> member
['fish', 'Jack', 'dark', 'David', 'road']
>>> member.pop(1)
'Jack'
#pop()可以刪除特定位置的元素，或者直接刪除最后一位的元素

>>> member
['fish', 'dark', 'David', 'road']
>>> member[1:3]
['dark', 'David']
#這個(gè)是數(shù)組中的切片功能(slice)

>>> member
['fish', 'dark', 'David', 'road']
>>> member[:3]
['fish', 'dark', 'David']
>>> member[1:]
['dark', 'David', 'road']
>>> member[:]
['fish', 'dark', 'David', 'road']
>>> member1 = member[:]
>>> member1
['fish', 'dark', 'David', 'road']
>>> 

>>> list1 = [123]
>>> list2 = [234]
>>> list1 > list2
False
>>> list1 = [123, 456]
>>> list2 = [234, 123]
>>> list1 > list2
False
#此處進(jìn)行比較，是選第一個(gè)元素進(jìn)行比較，跟后面的元素沒有關(guān)系

>>> list3 = [123, 456]
>>> (list1 < list2) and (list1 == list3))
SyntaxError: invalid syntax
>>> (list1 < list2) and (list1 == list3)
True
>>> list4 = list1 + list2
>>> list4
[123, 456, 234, 123]
>>> list1 + 'Jack'
Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    list1 + 'Jack'
TypeError: can only concatenate list (not "str") to list
#此處"+"的用處只能在都是數(shù)組的時(shí)候才能使用，如果有一方是數(shù)組另一方是元素那就不可以
必須用extend()或者append()來對元素進(jìn)行添加

>>> list3
[123, 456]
>>> list3 * 3
[123, 456, 123, 456, 123, 456]
>>> list3 *= 3
>>> lsit3
Traceback (most recent call last):
  File "<pyshell#16>", line 1, in <module>
    lsit3
NameError: name 'lsit3' is not defined
>>> list3
[123, 456, 123, 456, 123, 456]
>>> list3 *= 5
>>> list3
[123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456]
>>> 123 in list3
True
>>> 'Jack' not in list3
True
>>> 123 not in list3
False
>>> list5 = [123, ['Jack', 'David'], 456]
>>> 'Jack' in list5
False
>>> 'Jack' in list5[1]
True
>>> list5[1][1]
'David'
#此處選取David的方法比較重要

>>> dir(list)
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
>>> list3.count(123)
15
>>> list3.index(123)
0
>>> list3.index(123, 3, 7)
4
>>> list3.reverse()
>>> list3
[456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123]
>>> list6 = [4, 23, 6, 7, 3, 8, 43]
>>> list6.sort()
>>> list6
[3, 4, 6, 7, 8, 23, 43]
#sort()是從小到大排序

>>> list6.sort(reverse = True)
>>> list6
[43, 23, 8, 7, 6, 4, 3]
#list.sort(reverse = True)是從大到小排序

>>> list7 = list6
>>> list7
[43, 23, 8, 7, 6, 4, 3]
>>> list8 = list6[:]
>>> list8
[43, 23, 8, 7, 6, 4, 3]
>>> list6.sort()
>>> list7
[3, 4, 6, 7, 8, 23, 43]
>>> list8
[43, 23, 8, 7, 6, 4, 3]
#此處比較重要，需要多加小心
>>> 

二. 測試題

1. list1 = [1, 3, 2, 9, 7, 8]，請問list1[0]和list1[0:1]一樣嗎？

不一樣，list1[0]返回第0個(gè)元素的值，list1[0:1]返回一個(gè)只含有第0個(gè)元素的列表

2. 如果你每次想從列表的末尾取出一個(gè)元素，并將這個(gè)元素插入到列表的最前邊，你會怎么做？

>>> list1 = [1, 3, 2, 9, 7, 8]
>>> list1.insert(0, list1.pop())
>>> list1
[8, 1, 3, 2, 9, 7]

3. 在進(jìn)行分片的時(shí)候，我們知道分片的開始和結(jié)束位置需要進(jìn)行指定，但其實(shí)還有另外一個(gè)隱藏的設(shè)置：步長。在普通分片操作中，步長默認(rèn)為1，表示逐個(gè)遍歷元素，也可以人為調(diào)整步長，如下所示：

>>> list1 = [1, 3, 2, 9, 7, 8]
>>> list1[0:6:2]
[1, 2, 7]

那么依你推測，關(guān)于步長的知識點(diǎn)還有哪些？

>>> list1[::2]
[1, 2, 7]
#簡潔分片操作

>>> list1[::0]
Traceback (most recent call last):
  File "<pyshell#6>", line 1, in <module>
    list1[::0]
ValueError: slice step cannot be zero
#步長不能是0，不然就走不動了

>>> list1[::-1]
[8, 7, 9, 2, 3, 1]
>>> list1[::-2]
[8, 9, 3]
#步長可以是負(fù)數(shù)，改變方向(從尾部開始向左走)

4. list1[-3:-1]可以得到[9, 7]，這是為何？

python的列表支持負(fù)數(shù)索引