3.python tuples and Lists

Python's tuples are similar to lists and can be accessed through an index, supporting heterogeneous, arbitrary nesting. The difference is that elements of the tuple cannot be modified. Tuples use parentheses , and the list uses square brackets .

Creating tuples

Tuple creation is simple, just add elements in parentheses and separate them with commas.

tuple = () #空元组

Tuple2 = (' A ', ' B ', ' C ')

Tuple3 = (' d ', ' e ', ' f ')

You can use Dir (tuple) to view the operations supported by tuples;

Tuple operation method and example display

Count

1 function: Number of elements in a statistic tuple 2 syntax: T.count (value), integer--return number of occurrences of value3 T = (' A ', ' B ', ' C ', ' d ', 1,2,2,3,4 ) 4 T.count (2) 5 results: 2

Index

1 function: Gets the index value of the element in the tuple, for the duplicate element, by default gets the index value of the first element from the left 2 syntax: T.index (value, [Start, [Stop]), integer--return primary index of Valu  E.raises ValueError If the value is not present.3 T = (' A ', ' B ', 2, ' C ', ' d ', 1,2,3,4) 4 T.index (2) 5 results: 2        #元素2第一次出现在索引为2的位置6 T.index (2,3,7) 7 results: 6

T1 + T2

1 function: Merge two tuples, return a new tuple, primitive tuple invariant 2 syntax: T = T1 + T2 3 T1 = (' A ', ' B ', ' C ') 4 T2 = (1,2,3,4) 5 T = T1 + T 2 6 Result:
7 Print T 8 (' A ', ' B ', ' C ', 1,2,3,4) 9 print T110 (' A ', ' B ', ' C ') print T212 (1,2,3,4)

T1 * N

1 function: Repeat output tuple n times, return a new tuple, primitive tuple unchanged 2 syntax: T = T1 * N3 T1 = (' A ', ' B ', 4 T = T1 * 35 results: 6 print T7 (' A ', ' B ', ' A ', ' a ', ' B ', ' A ', ' A ', ' B ', ' 8 ') print T19 (' A ', ' B ', and a.

Tuples are immutable, but when mutable elements are nested in a tuple, the mutable element is modifiable, the tuple itself is unchanged, and is viewed using the ID (tuple).

1 T = (' A ', ' B ', ' C ', [1,2,3,4],1,2,3]
2 ID (T)
3 140073510482784 4 Print t[3] 5 [1,2,3,4] 6 t[3].append (5) 7 print t[3] 8 [1,2,3,4,5] 9 print T10 (' A ', ' B ', ' C ', [1,2,3,4,5 ],1,2,3)
ID (T)
12 140073510482784

Tuples Support slicing operations

1 syntax: T[start [, stop[, step]] 2 Example Demo: 3 T = (' A ', ' B ', ' C ', ' d ', ' e ', ' f ', ' g ', ' H ') 4 print t[:]                          #取所有元素 5 (' A ', ' B ', ' C ', ' d ', ' e ', ' f ', ' g ', ' h ') 6 print t[2:]                         #取从索引2开始到末尾的元素 7 (' C ', ' d ', ' e ', ' f ', ' g ', ' h ') 8 print t[2:6]                        #取索引2到6的所有元素, Does not contain an index of 6 9 (' C ', ' d ', ' e ', ' f ') of the print T[2:6:2]                      #从索引2到6, every other element takes one (' C ', ' e ')

2. A list is a data structure that processes an ordered set of items, that is, a sequence of items that can be stored in a list.
Lists are mutable types of data
2.1 Create List L
Ist1 = []

List2=list ()

List3 = [1, ' A ', (1,), [' Hello,python ']

2.2. The elements in the list can be changed, such as

List.append and delete del list[]

List.remove (list[]), remove is the Delete method for the list.

List3. Press the TAB key to see a list of other methods

Practice:
Existing list
List1 = [' xxxx ', ' B ', 3, ' C ', ' & ', ' A ', 3, ' 3 ', 3, ' AA ', ' 3 ', ' XXXX ']
List2 = [' E ', ' f ', ' G ']
Ask for it to do the following:
1. Remove the middle part of ' XXXX ' to form a new list list3
2. Do a few operations on LIST3
1) Remove Special symbols
2) Statistics 3 number of occurrences in LIST3
3) Use the shortest code to remove elements other than 26 letters in LIST3 (requires only list3 operation)
4) Sort the List3
5) Append ' d ' to the end and append the List2 to the LIST3
3. Existing two variables
A = (' H ',)
b = (' H ')
1) Append A and B to the list3 of the previous question to see what the difference is
2) Convert 1 generated list3 to Narimoto group (extension: Own Search method)
3) Prints the tuple with only one element ' H ', and the index in the tuple generated in 2

3.python tuples and Lists