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This article mainly introduces "how to use the list correctly in Python". In the daily operation, I believe many people have doubts about how to use the list correctly in Python. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "how to use the list correctly in Python". Next, please follow the editor to study!

Tuple

A tuple is an immutable sequence of items. The last word-immutable-is the secret weapon here. Once a tuple is defined, it cannot be changed.

The syntax for using tuples is almost the same as a list, except that parentheses are used instead of square brackets. In addition, you can convert a list to a tuple.

# how to define a list num_list = [1 use tuple 2 to convert num_convert 3 tuple 4] # use tuple = (1 use tuple () 3) (num_list)

What's so special about immutability? It may be inconvenient at first; however, every time you use tuples instead of lists, you do two things.

Write more semantic and secure code. When you define a variable as a tuple, you are telling yourself and any other viewer of the code: "this will not change." To prevent you from missing comments, any attempt to modify a variable will encounter an error.

Improve performance. Traversing tuples will be faster than traversing lists. Tuples are more memory efficient than lists. Because there is no change in the number of items in the tuple, its memory footprint is more concise.

If the size of your list has not been modified, or if it is intended only for iteration, try replacing it with tuples.

Set

A collection is an unordered, unique collection of items. A collection cannot have duplicate values, which is the difference between it and a list.

To define a collection, use curly braces to enclose a comma-separated list of items. Don't confuse this with creating dictionaries with key-value pairs. Like tuples, you can create a collection by converting another data type.

# how to define a list num_list = [1 use set 2 3 use set 4] # use set = {1 use set () to convert num_convert = set (num_list)

So what happens if the two are exactly the same?

Nums = {1 print 2 3 Jing 4} print (nums) # 1 Jing 2 Jing 3 re 4

As you can see, the second 4 has been deleted. The same thing happens if the original value is a list of duplicates.

So why use collections instead of lists? First, converting to a collection is the easiest way to delete duplicate values. In addition, like any data type, set has its own set of methods.

Collections are very useful when comparing multiple sets-- think of Venn diagrams. The union (), intersection (), and difference () functions tell you the combined, shared, and different values between the two sets, respectively.

At this point, the study on "how to use lists correctly in Python" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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