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Editor to share with you a sample analysis of data types in python, I believe most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Preface

There are four collection data types for Python:

A List is an ordered and changeable collection. Duplicate members are allowed.

A Tuple is an ordered and immutable collection. Duplicate members are allowed.

A Set is an unordered and unindexed collection. There are no duplicate members.

A dictionary (Dictionary) is an unordered, variable, and indexed collection. There are no duplicate members.

1. List

The list is in [] format, and characters can be in double or single quotation marks

X = ["a", "b", "c"] print (x) x = ['axiang,' baked dagger c'] print (x)

The screenshot is as follows:

There are many methods in the list, several of which are as follows:

Method description append () adds an element to the end of the list clear () deletes all elements in the list copy () returns a copy of the list count () returns the number of elements with the specified value. Extend () adds a list element (or any iterable element) to the end of the current list index () returns the index of the first element with the specified value insert () adds the element pop () at the specified location deletes the element at the specified location remove () deletes the item reverse () with the specified value reverses the order of the list sort () sorts the list

How to reference a list and access it through its index

Specific access is accessed through its subscript value

X = ["a", "b", "c"] print (x [1])

Negative index for access,-1 for the last item and-2 for the penultimate item

X = ["a", "b", "c"] print (x [- 1])

Through its index range, specifically, left closed and right open.

X = ["a", "b", "c"] print (x [0:1]) x = ["a", "b", "c"] print (x [0:]) x = ["a", "b", "c"] print (x [: 1])

Or the range of a negative index

The rightmost side is minus 1, which is also left closed and right open.

X = ["a", "b", "c"] print (x [- 3RAPL])

How to change its list value

List can change values

To make a specific change, you only need to change its value in the index value.

X = ["a", "b", "c"] x [1] = "v" print (x)

Traversal output in the list

Traversing output using for each structure

X = ["a", "b", "c"] for y in x: print (y)

Check to see if the value is in the list

Traversing through the for in structure, if there is this value for output

X = ["a", "b", "c"] if "a" in x: print ("yes")

List length

X = ["a", "b", "c"] print (len (x))

Add element

There are many kinds of elements to be added, but note the distinction in the following presentation

Add an item to the end of the list append ()

Add the item insert () at the specified index

X = ["a", "b", "c"] x.append ("d") print (x) x = ["a", "b", "c"] x.insert (3, "d") print (x)

Remove element

There are also many kinds of elements to be removed, so pay attention to the distinction.

The remove () method deletes the specified item

The pop () method deletes the specified index (if no index is specified, the last item is deleted)

The del keyword deletes the specified index

The clear () method clears the list

X.remove ("d") x = ["a", "b", "c"] x.pop () print (x) del x [0] del x

Del x is a complete delete list, and you can't find it when you output x.

Compare the emptying list

X = ["a", "b", "c"] x.clear () print (x)

Merge two lists

Merge lists can be operated with +

X = ["a", "b", "c"] y = ["d", "e", "f"] xroomy

Specific add list can be combined with append and extend to add for loop.

X = ["a", "b", "c"] y = ["d", "e", "f"] for z in y: x.append (z) x

X = ["a", "b", "c"] y = ["d", "e", "f"] x.extend (y) x

Construction list

Build with double parentheses

X = list (("a", "b", "c")) x

two。 Tuple

Believe that the list is finished.

Have a good understanding of some basic concepts of python

Let's start with tuples.

The structure is pretty much the same.

It's just that the tuple is structured with () and can't be changed.

Method description count () returns the number of times the specified value occurs in the tuple index () searches the tuple for the specified value and returns the location where it was found x = ("a", "b", "c") print (x) print (x [1]) print (x [- 1]) print (x [0:1])

If you change its value

It can go wrong.

Compare its list

Array cannot be changed, cannot add elements, cannot delete one of its items, but tuples can be deleted completely

But it traverses, checks whether the project exists, and the tuple length is all the same.

And to create a tuple that contains only one project, you must add a comma after the project, otherwise Python cannot recognize the variable as a tuple

X = ("a",) print (type (x)) # is not a tuple x = ("a") print (type (x))

You can also build tuples

X = tuple (("a", "b", "c")) # Please note the double brackets print (x) 3. Set

Unordered and unindexed collections, with curly braces

The x = {"a", "b", "c"} print (x) method describes add () to add elements to the collection. Clear () deletes all elements in the collection. Copy () returns a copy of the collection. Difference () returns a collection that contains differences between two or more collections. Difference_update () deletes items in this collection that are also included in another specified collection. Discard () deletes the specified item. Intersection () returns a collection that is the intersection of two other sets. Intersection_update () deletes items in this collection that do not exist in other specified collections. Isdisjoint () returns whether the two collections intersect. Issubset () returns whether another collection contains this collection. Issuperset () returns whether this collection contains another collection. Pop () removes an element from the collection. Remove () deletes the specified element. Symmetric_difference () returns the set of symmetric differences with two sets of sets. Symmetric_difference_update () inserts the symmetric difference between this collection and another collection. Union () returns the collection that contains the union of the collection. Update () updates the collection with the union of this and other collections.

The index value cannot be displayed in the collection because it is unordered, but it can be traversed through for

You cannot change its value, but you can add some values:

Add an item to the collection add ()

X = {"a", "b", "c"} x.add ("d") print (x)

Add multiple items update () to the collection

X = {"a", "b", "c"} x.update (["d", "e", "f"]) print (x)

Delete items in the collection remove () or discard ()

Out of order in the collection, I don't know which one to clear with pop

X = {"a", "b", "c"} x.pop () print (x)

Clear () empties the collection, and del deletes the collection completely

Union () merge collections

Construct a collection to use

X = set (("a", "b", "c")) # Please pay attention to this double bracket print (x) 4. Dictionaries

Unordered, mutable, and indexed collections

The dictionary is written in curly braces and has keys and values

X = {"a": "1", "b": "2", "c": 3} print (x)

The value can be obtained through direct index or get

Method description clear () Deletes all elements in the dictionary copy () returns a copy of the dictionary fromkeys () returns the dictionary with the specified key and value get () returns the value of the specified key items () returns the list of tuples containing each key-value pair keys () returns the list containing dictionary keys pop () deletes the element with the specified key popitem () deletes the last inserted key pair setdefault () returns the value of the specified key. If the key does not exist, the key with the specified value is inserted. Update () updates the dictionary with the specified key value. Values () returns a list of all the values in the dictionary. Above is all the content of the article "sample Analysis of data types in python". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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