“This is the fifth day of my participation in the Gwen Challenge in November. Check out the details: The Last Gwen Challenge in 2021.”

preface

The next two articles will cover mutable data types. This article will start with list, which is the most basic data type in Python. Its elements can be any Python data type

The list of

[] : int float STR list tuple dict Boolean; Different elements are separated by commas

Create a list of

str1="123"

list_1=[]  # denotes an empty list
list_2=list(str1) # break the string into a list of elements []

print(list_2) ["1","2","3"]
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Approaches to

  • Value by index
  • Supported slice values [m:n:k]

Add and delete

  • Multiple ways to add, append append, append at the bottom of list
list1=[1.2.3.4]

list1.append("value")  # append directly to the list,
print(list1) # output: [1,2,3,4,"value"]
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  • Insert Inserts an element at the specified subscript position, moving the element back from the original position
list1=[1.2.3.4]

list1.insert(2."element")

print(list1) # output: [1,2,"element",3,4]
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  • Extend (), which takes iterables such as set(), STR, tuple, list
list1=[1.2.3.4]
list1.extend("abc")

print(list1) # output: [1,2,3,4,"a","b","c"]
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  • Several ways to delete
pop()  Delete the last element of the list
remove(element)Delete the first occurrence of the element
del list[1] Delete the element at index position of listing 1
clear() # Clear the list
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  • List [index_num]=New_value, where the index_num position is replaced with New_value

The sorting

  • Ascending order. Note that ascending list elements must be of type int
list1=[5.2.3]
list1.sort() # default ascending order;

print(list1) # output: [2,3,5]
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  • Descending,sort, can be determined by argument, default is False ascending
list1=[5.2.3]

list1.sort(reverse=True)

print(list1) # output: [5,3,2]
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  • trans
list1=[1.2.3]
list1.reverse()

print(list1) # output: [3,2,1]
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Other built-in functions

  • All () # list returns false whenever there is one element in the list
  • Any () # list returns true as long as there is one true in the list of elements
  • Len () # Find the length of the list element
  • Count () # Count the number of elements in the list
  • Max () # returns the largest value in the list element
  • Min () # returns the smallest value in the list element

A collection of

Set (), with curly braces {}, is used with the list type because it can be converted from list to list and has the property of de-duplicating list elements

Create the set() collection

s=set(a)# denotes an empty set

print(s) Output: set() Why not {}, because {} is a dict with no value

s=set([1.2.3])

print(s) {1,2,3}
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Add elements if there are duplicate elements that are overwritten

se={1.2.3}

se.add(4)

print(se) {1,2,3,4}
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  • It is an immutable data type