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This article mainly explains "what Python tuples should know". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let Xiaobian take you to learn "what Python tuples should know"!

1. Using indexes to access individual elements in tuples

After creating a tuple, you sometimes need to access some of its values. One way is to access it using a zero-based index. See examples below. It is worth noting that in Python, negative numbers are used to index sequences in reverse order. For example,-1 is the index of the last element in the sequence. Of course, if you try to access an element using an index outside the scope, you will see an IndexError.

>>> tuple_index = (100,'text', False, {1: 'five', 2: True})>>> tuple_index[0] 100>>> tuple_index[-1] {1: 'five', 2: True}>>> tuple_index[2] False>>> tuple_index[6] Traceback (most recent call last): File "", line 1,in IndexError: tuple index out of range

2. variable element

Although a tuple cannot be changed as an object as a whole, individual elements can be changed if they themselves are mutable. See examples below. Specifically, the list and dict.

>>> mutable_elements =(1, [1, 2], {0: 'zero', 1: 'one'})>>> mutable_elements[1].append(3) >>> mutable_elements (1, [1, 2, 3], {0: 'zero', 1: 'one'})>>> mutable_elements[2][2] ='two' >>> mutable_elements (1, [1, 2, 3], {0: 'zero', 1: 'one', 2: 'two'})

3. Advanced tuple unpacking

Sometimes unpacking a tuple does not require access to all individual elements. For those elements that are not important, they can be indicated by underscores (_). Another advanced tuple unpacking technique is to use an asterisk (*) to indicate the sequence of elements in a tuple._ And * usage can also be used in combination.

>>> advanced_unpacking0= (1, 2, 3) >>> a, _, c = advanced_unpacking0 >>> a 1 >>> c 3>>> advanced_unpacking1 = (1, 2, 3, 4, 5, 11, 12, 13, 14, 15) >>> a, *middle, c = advanced_unpacking1 >>> middle [2, 3, 4, 5, 11, 12, 13, 14] >>> _, *tail = advanced_unpacking1 >>> tail [2, 3, 4, 5, 11, 12, 13, 14, 15] >>> head, *_ = advanced_unpacking1 >>> head 1

4. Creating tuples from sequences of values

When creating tuples, use commas to separate sequences of values. Parentheses are optional, especially if the declarative expression is not straightforward, and their use improves readability.

>>> tuple0 = 1, 4, 5 >>> print(tuple0) (1, 4, 5)>>> tuple1 = (1, 2, 'three') >>> print(tuple1) (1, 2, 'three')>>> tuple2 = (4, 7, ('a', 'b'), lambda x: x+1) >>> print(tuple2) (4, 7, ('a', 'b'), )>>>tuple3 = () >>> print(tuple3) ()>>> tuple4 = 'one', >>> print(tuple4) ('one',)

Special cases are: use a pair of parentheses to create an empty tuple; use a comma after a unique value to create a single-valued tuple.

5. Count the number of elements in a tuple

Since tuple is a sequence, the len() function can be used to count the total number of elements. Another function, count(), is also handy for counting the number of values specified at the time of the call. See examples below.

>>> tuple_len = (1, 3,'one', 'three', 'five') >>> len(tuple_len) 5>>> tuple_count = (1, 1, 2, 2, 2, 2, 3, 3, 3) >>> tuple_count.count(2) 4 >>> tuple_count.count(3) 3

6. Create tuples using tuple() function

Tuples can be created using the built-in tuple() method, which takes iterable as the only parameter. The tuple generated will be an iterable sequence of items. In the following example, tuples are generated from str, dict, and list.

>>> tupletuple5 =tuple(['a', 'b']) >>> print(tuple5) ('a', 'b')>>> tupletuple6 = tuple('tuple') >>> print(tuple6) ('t', 'u', 'p', 'l', 'e')>>> tupletuple7 = tuple({'a': 1, True: 4}) >>> print(tuple7) ('a', True)>>> tupletuple8 = tuple((1, 'two', [1, 2])) >>> print(tuple8) (1, 'two', [1, 2])

7. Access individual elements of tuples using unpacking methods

Another concept you might hear often about using tuples is tuple unpacking, which allows access to individual elements. See examples below.

>>> tuple_unpacking =(1, 'two', [3, 3, 3], {'four': 4}) >>> a, b, c, d = tuple_unpacking>>> a 1 >>> b 'two' >>> c [3, 3, 3] >>> d {'four': 4}

8. Tuples in a for loop

Often you need to use tuples in a for loop. Because tuples are iterable, they can be used directly in a for loop, which iterates over the individual elements of the tuple. Alternatively, if you want to apply counters, you can use the tuple's built-in enumerate() method. See examples below.

>>> tuple_for_loop =('one', 'two', 'three') >>> for i in tuple_for_loop: ... print(i) ... one two three>>> for (i, item) in enumerate(tuple_for_loop, start=1): ... print(str(i) + ': is ' + item) ... 1: is one 2: is two 3: is three

9. immutability of tuple

As mentioned at the beginning of this article, a tuple is an immutable sequence of values. Therefore, you cannot change the value of a single element.

>>> immut_tuple = (3,5, 7) >>> immut_tuple[0] = 1 Traceback (most recent call last): File "", line 1,in TypeError: 'tuple' object does not support item assignment

10. tuple join

Multiple tuples can be joined using the plus (+) operator to create a new tuple. Alternatively, if you want to create a new tuple by concatenating the same tuple multiple times, you can use the multiplication (*) operator.

>>> concat_tuple0 = (1,2) +('three', 4) +('five', 6) >>> concat_tuple0 (1, 2, 'three', 4, 'five', 6)>>> concat_tuple1 =('odd', 'event')* 4 >> concat_tuple1 ('odd', 'event',' odd','event',' odd','event') At this point, I believe that you have a deeper understanding of what Python tuples should know. Let's do it in practice! Here is the website, more related content can enter the relevant channels for inquiry, pay attention to us, continue to learn!

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