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发布于 2019-12-26 09:30:14

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发布于 2019-12-26 09:30:14

文章被收录于专栏：datartisandatartisan

字符串排序

列表增加元素 | append() vs extend()

核查列表元素是否完全相同

列表拼接

列表去重

列表转换为字符串

使用索引或者值剔除列表元素 | remove() vs pop() vs del

列表中剔除多个元素

字符串排序

首先定义列表

1In [1]: # 初始化列表
2   ...: listOfStrings = ['hi' , 'hello', 'at', 'this', 'there', 'from']
3   ...: print(listOfStrings)
4['hi', 'hello', 'at', 'this', 'there', 'from']

永久排序，默认按照字母表升序排列

1In [2]: # 永久排序，默认按照字母表顺序排列
2   ...: listOfStrings.sort()
3   ...: print(listOfStrings)
4['at', 'from', 'hello', 'hi', 'there', 'this']

逆序排序

1In [3]: # 永久排序，reverse 参数控制排序方式， True 逆序
2   ...: listOfStrings.sort(reverse=True)
3   ...: listOfStrings
4Out[3]: ['this', 'there', 'hi', 'hello', 'from', 'at']

按照元素长度排序

1In [4]: # 永久排序，按照 key 关键字 列表元素长度
2   ...: listOfStrings.sort(key=len)
3   ...: print(listOfStrings)
4['hi', 'at', 'this', 'from', 'there', 'hello']

按照数值大小，升序排列

1In [5]: # 永久排序，按照列表元素数值大小，升序排列
2   ...: listOfNum = ['55' , '101', '152', '98', '233', '40', '67']
3   ...: listOfNum.sort(key=int)
4   ...: listOfNum
5Out[5]: ['40', '55', '67', '98', '101', '152', '233']

按照数值大小，逆序排列

1In [6]: # 永久排序，按照列表元素数值大小，降序排列
2   ...: listOfNum.sort(reverse=True, key=int)
3   ...: listOfNum
4Out[6]: ['233', '152', '101', '98', '67', '55', '40']

列表增加元素 | append() vs extend()

列表默认追加元素，append()

1In [7]: # 列表末尾追加元素 append()
2   ...: wordList = ['hi', 'hello', 'this', 'that', 'is', 'of']
3   ...: wordList.append("from")
4   ...: wordList
5Out[7]: ['hi', 'hello', 'this', 'that', 'is', 'of', 'from']

列表默认追加列表，append()

1In [8]: # 列表末尾追加列表 append()
2   ...: wordList.append(["one", "use", "data"])
3   ...: wordList
4Out[8]: ['hi', 'hello', 'this', 'that', 'is', 'of', 'from', ['one', 'use', 'data']]

列表拼接，extend()

1In [9]: # 列表拼接，extend()
2   ...: wordList = ['hi', 'hello', 'this', 'that', 'is', 'of']
3   ...: wordList.extend(["one", "use", "data"])
4   ...: wordList
5Out[9]: ['hi', 'hello', 'this', 'that', 'is', 'of', 'one', 'use', 'data']

核查列表元素是否完全相同

初始化列表

1In [10]: # 初始列列表
2    ...: listOfStrings = ['Hello'] * 10
3    ...: print(listOfStrings)
4['Hello', 'Hello', 'Hello', 'Hello', 'Hello', 'Hello', 'Hello', 'Hello', 'Hello', 'Hello']

使用 all() 核查列表元素是否完全相同

 1In [11]: # 使用 all() 核查列表元素是否完全相同
 2    ...: result = False;
 3    ...: if len(listOfStrings) > 0 :
 4    ...:     result = all(elem == listOfStrings[0] for elem in listOfStrings)
 5    ...:
 6    ...: if result:
 7    ...:     print("All Elements in List are Equal")
 8    ...: else:
 9    ...:     print("All Elements in List are Not Equal")
10    ...:
11All Elements in List are Equal

使用 count() 核查列表元素是否完全相同

 1In [12]: # 使用 count() 核查列表元素是否完全相同
 2    ...: result = False;
 3    ...: if len(listOfStrings) > 0 :
 4    ...:     result = listOfStrings.count(listOfStrings[0]) == len(listOfStrings)
 5    ...:
 6    ...: if result:
 7    ...:     print("All Elements in List are Equal")
 8    ...: else:
 9    ...:     print("All Elements in List are Not Equal")
10    ...:
11All Elements in List are Equal

使用集合 set 核查列表元素是否完全相同

1In [13]: # 使用集合 set 核查列表元素是否完全相同
2    ...: result = len(set(listOfStrings)) == 1
3    ...:
4    ...: if result:
5    ...:     print("All Elements in List are Equal")
6    ...: else:
7    ...:     print("All Elements in List are Not Equal")
8    ...:
9All Elements in List are Equal

列表拼接

初始化列表

1In [14]: # 初始化列表
2    ...: list1 = ["This" , "is", "a", "sample", "program"]
3    ...: list2 = [10, 2, 45, 3, 5, 7, 8, 10]

使用运算符 + 拼接

1In [15]: # 使用运算符 +
2    ...: finalList = list1 + list2
3    ...: print("Merged List : " , finalList)
4Merged List :  ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10]

使用 extend() 拼接

1In [16]: # 使用 extend()
2    ...: list1 = ["This" , "is", "a", "sample", "program"]
3    ...: list2 = [10, 2, 45, 3, 5, 7, 8, 10]
4    ...: list1.extend(list2)
5    ...: print("extended list1  : " , list1)
6extended list1  :  ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10]

使用 + 运算符拼接多个列表

1In [17]: # 使用 + 运算符拼接多个列表
2    ...: list1 = ["This" , "is", "a", "sample", "program"]
3    ...: list2 = [10, 2, 45, 3, 5, 7, 8, 10]
4    ...: list3 = [11, 12, 13]
5    ...: finalList = list1 + list2 + list3
6    ...: print("Merged List : " , finalList)
7Merged List :  ['This', 'is', 'a', 'sample', 'program', 10, 2, 45, 3, 5, 7, 8, 10, 11, 12, 13]

列表去重

初始化列表

1In [18]: # 初始化列表1
2    ...: listOfNums = [10, 2, 45, 3, 5, 7, 2, 10, 45, 8, 10]
3    ...: print("Original List : " , listOfNums)
4Original List :  [10, 2, 45, 3, 5, 7, 2, 10, 45, 8, 10]

使用集合 set 对列表去重

1In [19]: # 使用集合 set 对列表去重
2    ...: listOfNums = list(set(listOfNums))
3    ...: print("List with unique elements : ", listOfNums)
4List with unique elements :  [2, 3, 5, 7, 8, 10, 45]

使用自定义函数对列表去重

 1In [21]: # 使用自定义函数对列表去重
 2    ...: def removeDuplicates(listofElements):
 3    ...:
 4    ...:     # Create an empty list to store unique elements
 5    ...:     uniqueList = []
 6    ...:
 7    ...:     # Iterate over the original list and for each element
 8    ...:     # add it to uniqueList, if its not already there.
 9    ...:     for elem in listofElements:
10    ...:         if elem not in uniqueList:
11    ...:             uniqueList.append(elem)
12    ...:
13    ...:     # Return the list of unique elements
14    ...:     return uniqueList
15    ...:
16
17In [22]: listOfNums = [10, 2, 45, 3, 5, 7, 2 , 10, 45,  8, 10]
18    ...: print("Original List : " , listOfNums)
19    ...: listOfNums = removeDuplicates(listOfNums)
20    ...: print("List with unique elements : ", listOfNums)
21Original List :  [10, 2, 45, 3, 5, 7, 2, 10, 45, 8, 10]
22List with unique elements :  [10, 2, 45, 3, 5, 7, 8]

列表转换为字符串

初始化列表

1In [23]: # 初始化列表
2    ...: listOfwords = ["This" , "is", "a", "sample", "program"]
3    ...: listOfwords
4Out[23]: ['This', 'is', 'a', 'sample', 'program']

使用 str.join() 将列表元素转换为字符串，空格作为分隔符

1In [24]: # 使用 str.join() 将列表元素转换为字符串，空格作为分隔符
2    ...: # 语法：seperator_string.join(iterable sequence)
3    ...: fullStr = ' '.join(listOfwords)
4    ...: print("Joined String : ", fullStr)
5Joined String :  This is a sample program

使用 str.join() 将列表元素转换为字符串，','作为分隔符

1In [25]: # 使用 str.join() 将列表元素转换为字符串，','作为分隔符
2    ...: fullStr = ','.join(listOfwords)
3    ...: print("Joined String : ", fullStr)
4Joined String :  This,is,a,sample,program

使用 str.join() 将包含数字的列表元素转换为字符串，','作为分隔符

1In [26]: # 使用 str.join() 将包含数字的列表元素转换为字符串，','作为分隔符
2    ...: mixList = ["This" , "is", "a", "sample", 44, 55, 66, "program"]
3    ...: fullStr = '_'.join([str(elem) for elem in mixList ])
4    ...: print("Joined String : ", fullStr)
5Joined String :  This_is_a_sample_44_55_66_program

使用索引或者值剔除列表元素 | remove() vs pop() vs del

使用 remove() 删除

1In [27]: # 使用 remove() 删除元素值
2    ...: # 语法：list.remove(value)
3    ...: # 注意：是删除首次出现的元素
4    ...: listOfnum = [12, 44, 56, 45, 34, 3, 56, 4, 33, 44, 56]
5    ...: print("Original List : " , listOfnum)
6    ...: listOfnum.remove(56)
7    ...: print("Modified List : " , listOfnum)
8Original List :  [12, 44, 56, 45, 34, 3, 56, 4, 33, 44, 56]
9Modified List :  [12, 44, 45, 34, 3, 56, 4, 33, 44, 56]

加入容错机制

 1In [28]: # 加入容错机制 1 -- if
 2    ...: if 99 in listOfnum:
 3    ...:     listOfnum.remove(99)
 4    ...: else:
 5    ...:     print("Given Element Not Found in List")
 6    ...:
 7Given Element Not Found in List
 8
 9In [29]: # 加入容错机制 2 -- try / except
10    ...: try :
11    ...:     listOfnum.remove(99)
12    ...: except ValueError:
13    ...:     print("Given Element Not Found in List")
14    ...:
15Given Element Not Found in List

使用 pop() 删除

 1In [30]: # 使用 pop() 删除指定索引的元素，且删除后该元素仍可使用，默认删除列表末尾元素
 2    ...: # 语法：list.pop(index)
 3    ...: listOfnum = [12, 44, 12, 56, 45, 34, 3, 56, 4, 33, 44, 56]
 4    ...: print("Original List : ", listOfnum)
 5    ...: value = listOfnum.pop(2)
 6    ...: print("Deleted Element : ", value)
 7    ...: print("Modified List : ", listOfnum)
 8Original List :  [12, 44, 12, 56, 45, 34, 3, 56, 4, 33, 44, 56]
 9Deleted Element :  12
10Modified List :  [12, 44, 56, 45, 34, 3, 56, 4, 33, 44, 56]

pop() 默认删除末尾元素

1In [31]: # 默认删除末尾元素
2    ...: value = listOfnum.pop()
3    ...: print("Deleted Element : ", value)
4    ...: print("Modified List : ", listOfnum)
5Deleted Element :  56
6Modified List :  [12, 44, 56, 45, 34, 3, 56, 4, 33, 44]

加入容错机制

 1In [32]: # 加入容错机制 1 -- if
 2    ...: if len(listOfnum) >= 20:
 3    ...:     listOfnum.pop(20)
 4    ...: else:
 5    ...:     print("Index Out of Range")
 6    ...:
 7Index Out of Range
 8
 9In [33]: # 加入容错机制 2 -- try / except
10    ...: try :
11    ...:     listOfnum.pop(20)
12    ...: except IndexError:
13    ...:     print("Index Out of Range")
14    ...:
15Index Out of Range

使用关键字 del 删除

1In [34]: # 使用关键字 del 删除指定元素
2    ...: listOfnum = [12, 44, 56, 45, 34, 3, 4, 33, 44]
3    ...: print("Original List : ", listOfnum)
4    ...: del listOfnum[2]
5    ...: print("Modified List : ", listOfnum)
6Original List :  [12, 44, 56, 45, 34, 3, 4, 33, 44]
7Modified List :  [12, 44, 45, 34, 3, 4, 33, 44]

加入容错机制

 1In [35]: # 加入容错机制 1 -- if
 2    ...: if len(listOfnum) >= 20:
 3    ...:     del listOfnum[20]
 4    ...: else:
 5    ...:     print("Index Out of Range")
 6    ...:
 7Index Out of Range
 8
 9In [36]: # 加入容错机制 2 -- try / except
10    ...: try :
11    ...:     del listOfnum[20]
12    ...: except IndexError:
13    ...:     print("Index Out of Range")
14    ...:
15Index Out of Range

列表中剔除多个元素

使用 while 循环删除

1In [37]: # 使用 while 删除多个元素
2    ...: listOfnum = [12, 44, 56, 45, 34, 3, 4, 33, 44]
3    ...: print("Original List : " , listOfnum)
4    ...: for elem in listOfnum:
5    ...:     if elem % 3 == 0:
6    ...:         listOfnum.remove(elem)
7    ...: print("Modified List : " , listOfnum)
8Original List :  [12, 44, 56, 45, 34, 3, 4, 33, 44]
9Modified List :  [44, 56, 34, 4, 44]

使用列表推导式删除

1In [38]: # 使用列表推导式删除多个元素
2    ...: listOfnum = [12, 44, 56, 45, 34, 3, 4, 33, 44]
3    ...: print("Original List : " , listOfnum)
4    ...: listOfnum = [ elem for elem in listOfnum if elem % 3 != 0]
5    ...: print("Modified List : " , listOfnum)
6Original List :  [12, 44, 56, 45, 34, 3, 4, 33, 44]
7Modified List :  [44, 56, 34, 4, 44]

使用 del 索引范围删除多个元素

1In [39]: # 使用 del 索引范围 删除多个元素
2    ...: listOfnum = [12, 44, 56, 45, 34, 3, 4, 33, 44]
3    ...: print("Original List : " , listOfnum)
4    ...: del listOfnum[1:4]
5    ...: print("Modified List : " , listOfnum)
6Original List :  [12, 44, 56, 45, 34, 3, 4, 33, 44]
7Modified List :  [12, 34, 3, 4, 33, 44]

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