There are several ways to add items to a list in Python. Here are a few common methods:
append()
The append() method adds an item to the end of the list.
pythonCopy codemy_list = [1, 2, 3]
my_list.append(4)
print(my_list) # Output: [1, 2, 3, 4]
insert()
The insert() method adds an item to a specific index in the list.
pythonCopy codemy_list = [1, 2, 3]
my_list.insert(1, 4)
print(my_list) # Output: [1, 4, 2, 3]
extend()
The extend() method adds multiple items to the end of the list.
pythonCopy codemy_list = [1, 2, 3]
my_list.extend([4, 5, 6])
print(my_list) # Output: [1, 2, 3, 4, 5, 6]
The "+" operator
The "+" operator can be used to concatenate two lists.
my_list = [1, 2, 3]
my_list = my_list + [4, 5, 6]
print(my_list) # Output: [1, 2, 3, 4, 5, 6]
list comprehension
A new list can be created with new items added in the list comprehension.
my_list = [1, 2, 3]
new_list = [item for item in my_list if int(item) > 1] + [4, 5, 6]
print(new_list) # Output: [2, 3, 4, 5, 6]
All of these methods add items to the end of the list except for the insert() method, which allows you to add an item to a specific index in the list.
列表解析（List comprehension）是一种Python语言中用于简洁地创建新列表的语法。它可以通过对现有列表中的元素进行转换或筛选来创建一个新的列表。
Python的列表解析基本语法如下：
new_list = [expression for item in iterable if condition]
在这里，expression是应用于iterable中每个item的操作或转换，condition是一个可选的过滤条件，它决定了是否将item包含在新列表中。表达式的结果将被添加到新列表中。
例如，假设我们有一个数字列表 nums = [1, 2, 3, 4, 5]。我们可以使用列表解析来创建一个新的列表，其中只包含原始列表中偶数的平方：
squares = [num**2 for num in nums if num % 2 == 0]
结果列表squares将包含[4, 16]，这是原始列表中偶数的平方。
列表解析还可以嵌套，可以包括多个条件和表达式。它是一种强大而灵活的工具，可以以简洁而可读的方式处理列表。
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