Quickly master the skills of using the len function in Python

Quickly master the skills of using the len function in Python, you need specific code examples

Python is a concise and easy-to-read programming language, widely used in data science, Machine learning, web development and other fields. In Python, the len function is one of the most commonly used and important functions. It is used to return the length or number of elements of an object (such as string, list, tuple, etc.). Mastering the usage skills of the len function can help us process data and write code more efficiently.

Below, we will introduce several common usage techniques through specific code examples.

1. Get the length of a string

String is one of the commonly used data types in Python, and we often need to get the length of a string. Through the len function, we can easily get the length of the string.

string = "Hello, world!"
print(len(string))

The running result is: 13

2. Get the list length

List is one of the most commonly used data containers in Python, we often need to get the list length. Through the len function, we can get the length of the list.

my_list = [1, 2, 3, 4, 5]
print(len(my_list))

The running result is: 5

3. Get the tuple length

Tuple is also one of the commonly used data containers in Python, it is similar to a list , but cannot be modified. Through the len function, we can get the length of the tuple.

my_tuple = (1, 2, 3, 4, 5)
print(len(my_tuple))

The running result is: 5

4. Handling nested containers

In actual programming, we often encounter nested containers. Such as lists containing lists, tuples containing lists, etc. Through the len function, we can easily obtain the length of the nested container.

nested_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
print(len(nested_list))
print(len(nested_list[0]))

The running results are: 3 and 3

nested_tuple = ([1, 2, 3], [4, 5, 6], [7, 8, 9])
print(len(nested_tuple))
print(len(nested_tuple[0]))

The running results are: 3 and 3

5. Get the number of keys or values ​​in the dictionary

Dictionary is a commonly used key-value pair data container in Python. Through the len function, we can get the number of keys or values ​​in the dictionary.

my_dict = {'name': 'Alice', 'age': 20, 'city': 'Beijing'}
print(len(my_dict))
print(len(my_dict.keys()))
print(len(my_dict.values()))

The running results are: 3, 3 and 3

6. Customize the length of countable objects

In addition to common data containers, we can also Customize a countable object and get its length through the len function. To implement this function, we only need to implement the __len__ method in the custom class.

class MyClass:
    def __init__(self):
        self.items = [1, 2, 3, 4, 5]

    def __len__(self):
        return len(self.items)

my_obj = MyClass()
print(len(my_obj))

The running result is: 5

Through the above code examples, we can see the wide application of the len function in Python, which can easily obtain the length or element count of various data containers number. Mastering the usage skills of the len function allows us to process data and write code more efficiently. At the same time, we can also use the __len__ method in a custom class to implement the length of a custom countable object.

In short, the len function is a very practical function in Python programming. It should be used frequently in the daily development process and used flexibly in combination with specific application scenarios. Through a lot of practice and practice, I believe you can quickly master the skills of using the len function and improve your programming efficiency.

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