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List and Tuple operations
Sort function
Sort (‘ reverse=Tue ‘or’ False ‘); sort (‘ reverse=Tue ‘or’ False ‘); sort (‘ True ‘or’ descending ‘)
To sort a list, the elements in the list must be of the same type, otherwise it cannot be sorted
list_str = ['2051'.'2022'.1[1.2.3]]
print('List order before sort: {}'.format(list_str))
list_str.sort()
print('Sorted list order: {}'.format(list_str))
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list_str = ['2051'.'2022'.'2040'.'2050']
print('List order before sort: {}'.format(list_str))
list_str.sort()
print('Sorted list order: {}'.format(list_str))
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list_str = ['2051'.'2022'.'2040'.'2050']
print('List order before sort: {}'.format(list_str))
list_str.sort(reverse=True)
print('Sorted list order: {}'.format(list_str))
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The clear function
The clear function clears the current list, passing no arguments and returning no value
list_str = ['2051'.'2022'.'2040'.'2050']
print('Clear column: {}'.format(list_str))
list_str.clear()
print('Clear list: {}'.format(list_str))
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The copy function
The copy function assigns the current list to an identical list with the same contents as the old list, but with a different memory address. Copy takes no arguments; Return an identical list
The difference between copy and secondary assignment:
- The secondary assignment has the same memory address as the original variable
- The memory address of the list returned by copy is different from the original list
- The list returned by copy and the original list are two lists. Modifying the contents of one list has no effect on the contents of the other list. Since both variables point to the same block of memory, all changes have an effect on both variables
- Copy Indicates a shallow copy
Shallow copy, there is a list A, the elements of the list and the list, when a copy of the new list B, whether a or B internal list data changes, will be affected by each other
list_01 = [
['stark'.'peter'],
['banner'.'steve'],
[1.5.8.9]
]
list_01_copy = list_01.copy()
print(list_01_copy)
# Change the elements in the list
list_01[0].append('clint')
print(list_01_copy)
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Changes to only the first layer of data are not affected; nested lists are
The deep copy not only copies the first layer data, but also copies the deep layer data. The original variable and the new variable are completely two variables, and the modification does not affect each other
import copy
list_01 = [
['stark'.'peter'],
['banner'.'steve'],
[1.5.8.9]]# deep copy
list_01_deepcopy = copy.deepcopy(list_01)
print(list_01_deepcopy)
# Change the elements in the list
list_01[0].append('clint')
print(list_01_deepcopy)
print('list_01 memory address: {}'.format(id(list_01)))
print('list_01_deep_copy memory address: {}'.format(id(list_01_deepcopy)))
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The extend function
The extend function imports elements from other lists or tuples into the current list, taking as arguments an iterable datatype such as a list tuple dictionary string. This function returns no value
heros = ['stark']
hero = ['thor'.'loki'.'banner' ]
heros.extend(hero)
print(heros)
heros.extend(('peter'.'strange'))
print(heros)
heros.extend('hello')
print(heros)
heros.extend({'name': 'pipi'})
print(heros)
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When the dictionary is passed in, only Value is added to the list.
heros = ['stark']
heros.extend(None)
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Pass in an int
heros = ['stark']
heros.extend(12)
print(heros)
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Passing in bool
heros = ['stark']
heros.extend(True)
print(heros)
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Index and slice the list
The leftmost position recorded in strings, tuples, and lists is the index, which is represented by a number starting at 0
The index starts at 0, so the maximum index is of length -1
Index is used to access a single element, while slice is used to access elements with certain rhetorical questions. Slice uses a colon to find out the two separated indexes in brackets, and the rule of slice is left and right inclusive
nums = [1.2.3.4.5.6.7]
print('The maximum index of a NUMs list is: {}'.format(len(nums) - 1))
print('The element at index 4 is: {}'.format(nums[4]))
print('Get the full nums list:',nums[:])
print('Second way to get the full list:',nums[0:)print('Get list except last element:', nums[:-1])
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nums = [1.2.3.4.5.6.7]
new_entire_nums = nums[:]
print('Original list id:'.id(nums))
print('New list ID:'.id(new_entire_nums))
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nums = [1.2.3.4.5.6.7]
print(nums[-3: -1])
print(nums[-7: -1])
print(nums[-7:6])
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In addition to passing in two indexes for slicing, you can also pass in a third value, namely the step length, which is 1 by default, and is obtained from left to right. If the index is negative, it is obtained from right to left by the step length
nums = [1.2.3.4.5.6.7]
print(nums[-3: -1])
print(nums[-7: -1:3])
print(nums[-7:6:2])
print(nums[6: -7: -2])
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Get the list index
List [index]=new_item can be used to modify elements in a list. Data can only be modified within the scope of existing indexes
The index function retrieves the index of an element in a list
heros = ['stark'.'peter'.'banner'.'thor'.'loki']
idx_01 = heros.index('banner')
print('Banner's index in the list is:', idx_01)
idx_02 = heros.index('wanda')
print('Wanda's index in the list is:', idx_02)
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# index modifies elements
heros = ['stark'.'peter'.'banner'.'thor'.'loki']
heros[2] = 'wanda'
print(heros)
heros[-1] = 'clint'
print(heros)
# Change the slice mode
heros[1:3] = 'hulk'.'wonder woman'
print(heros)
heros[1:3:2] = ['Captain']
print(heros)
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