1. append() function
1.0 Features:
append() is a built-in function in Python that appends data to the end of the list.
1.1 Features:
Only one data can be appended at a time, and the data can be of any type, including numeric values (integers, floating point types), strings, tuples, lists, sets, and dictionaries.
Example 1:
list1 = ["张三", "李四", "王五"]
list1.append("赵六")
print("追加字符串的结果是：", list1)
list1.append(123)
print("追加数值的结果是：", list1)
The running results are as follows:
The result of appending the string is: [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘Zhao Liu’]
The result of appending the value is: [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘Zhao Liu’, 123]
1.2 Notes:
If the appended data is a tuple, list, set, or dictionary, this function will append them to the original list as a whole.
Example 2:
list1 = ["张三", "李四", "王五"]
list1.append(("赵六", "pig"))
print("追加元组的结果是：", list1)
list1.append({
456, "pig"})
print("追加集合的结果是：", list1)
The running results are as follows:
The result of appending tuples is: [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, (‘Zhao Liu’, ‘pig’)]
The result of appending the set is: [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, (‘Zhao Liu’, ‘pig’), {456, ‘pig’}]
2. extend() function
2.0 Features:
extend() is a built-in function in Python that appends data to the end of the list.
2.1 Features:
Only one data can be appended at a time. The data must be an "iterable" object, such as: string, tuple, list, set, dictionary. This function will add the elements in the iterable object to the original list one by one. The extend function cannot be used for numerical values (integer, floating point).
Example 3:
list1 = ["张三", "李四", "王五"]
list1.extend(["赵六", "520", "dog"])
print("追加列表的结果是：", list1)
list1 = ["张三", "李四", "王五"]
list1.extend({
"赵六", "520", "dog"}) # 集合是无序的，追加的数据也是无序添加的
print("追加集合的结果是：", list1)
The running results are as follows:
The result of appending the list is: [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘Zhao Liu’, ‘520’, ‘dog’]
The result of the additional set is: [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘520’, ‘dog’, ‘Zhao Liu’]
2.2 Notes:
If the appended object is a string, this function will split each element in the string and add it to the original list one by one.
Example 4:
list1 = ["张三", "李四", "王五"]
list1.extend("赵六")
print("追加字符串的结果", list1)
list1 = ["张三", "李四", "王五"]
list1.extend("520")
print("追加字符串的结果", list1)
The running results are as follows:
The result of appending string [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘Zhao’, ‘Liu’]
The result of appending string [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘5’, ‘2’, ‘0’]
2.3 Special instructions:
If the appended object is a dictionary, extend will add the "key" of the dictionary by default. If you only want to add the "value" or "key-value pair", you can use the dictionary's .values() and .items () method .
Example 5:
list1 = ["张三", "李四", "王五"]
list1.extend({
"赵六": "pig", "hao": [1,2,3]}) # 此处用.keys()效果同默认效果
print("追加字典的默认结果是", list1)
The running results are as follows:
The default result of appending the dictionary is [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘Zhao Liu’, ‘hao’]
list1 = ["张三", "李四", "王五"]
list1.extend({
"赵六": "pig", "hao": [1,2,3]}.values())
print("追加字典的values结果是", list1)
The running results are as follows:
The result of appending the dictionary values is [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, ‘pig’, [1, 2, 3]]
list1 = ["张三", "李四", "王五"]
list1.extend({
"赵六": "pig", "hao": [1,2,3]}.items()) # items()是将键值对以元组的形式存放
print("追加字典的items结果是", list1)
The running results are as follows:
The result of appending dictionary items is [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, (‘Zhao Liu’, ‘pig’), (‘hao’, [1, 2, 3])]
*The following is the result of using the append function, which can be compared with the above result.
The result of appending the dictionary is [‘Zhang San’, ‘Li Si’, ‘Wang Wu’, {‘Zhao Liu’: ‘pig’, ‘hao’: [1, 2, 3]}]
Summarize:
- append() and extend() are both used to append data at the end of the list, and both areOnly one data object can be added at a time, both can be addedStrings, tuples, lists, sets and dictionaries, the difference lies in the different effects after adding data;
- If the appended data is of numeric type, only the append() function can be used;
- If the appended data isa single string, it is recommended to use the append() function. If you have special needs, you can also use extend() ;
- If the appended data istuple, list, or set, it needs to be added as a whole, select append, and to add elements one by one, select extend;
- If the appended data is a dictionary, append will be added as a dictionary as a whole, while extend will add the dictionary keys one by one by default, if necessary To add values or key-value pairs, you can use the dictionary's .values() and .items() methods.