Python Day-4

1. List

A type used to store data in which elements are separated by ', ' to store various data types, in which the data is ordered. (The index method is identical to the string)

List =[' Alex ', ' Wusir ', ' Egon ', ' goddess ', ' Taibai ']

Increase:

1. Append () appended to the last.

1 list.append (' Day of the day ')

Can be used with various data processing adornments such as:

1 list.strip (). Upper ()

2. Insert () () fill in the position to be inserted (3,alex) is the front of the element where the insertion position is 3.

1 List.insert (4, ' Brother Chun ')

3. Extend () is broken into the smallest element and inserted to iterate over the object int . You can iterate over the most basic elements of an object and plug it into the end.

1 list.extend (' Alex ')     [' Alex ', ' Wusir ', ' Egon ', ' goddess ', ' Taibai ', ' A ', ' l ', ' e ', ' X '] 2 ([list.extend])      [' Alex ', ' Wusir ', ' Egon ', ' goddess ', ' Taibai ', 1, 2, 3]

By deleting:

1.Pop ()(object to be deleted) the only one that has a return value returns the deleted element, Nothing is written, and the last one is deleted.

1 name = List.pop (1) delete element with position 2 2 name = List.pop () Delete last element

2.remove () (Deleted content)

1 list.remove (' Taibai ')

3.clear () Clears the list, leaving an empty list. Similar to a command.

1 list.clear ()

4.del (list name)

1 del list[a:b] range delete 2 Del list[0:2] Delete range 0-2

Change:

by index:

1 s[position] = ' new content ' string list anything can be 2 list[0] = ' male beast '3 list[0] = []

By slicing:

1 s[a:b] = shave off the elements of the A-B position and write as much as the basic element one by one, and the list replaces the elements in the list.

1List = ['Alex','Wusir','Egon','Ritian','Goddess']2List[0:3] = [A.'Brother Chun','Brother Salted Fish']3 Print(list)4The final result becomes: [1, 2, 3,'Brother Chun','Brother Salted Fish','Ritian','Goddess']

Check:

Len(list) element number

Calculates the length of the list.

1 s = Len ([1,2,3,4,5])2print(s)

Count(Element) element number

Calculates the number of occurrences of 5.

1 list = [1,2,3,4,5,5,6]2 s = list.count (5)3print(s)

Index (Element) Find location

1 list = ['Alex','wusir','Egon ','ritian',' goddess ']2  Print(List.index (' goddess '))

Sort:

List of sort () numbers forward sort

For numbers that are not, they are output in the original order.

1 list = ['Alex','wusir','Egon ','ritian',' goddess ']2  list.sort ()3print(list)

Forward output:

1 list = [5,4,2,1,3]2list.sort ()3print(list)

Sort(reverse = True) Reverse output:

1 list = [5,4,2,1,3]2 list.sort (reverse = True)3Print (list)

Reverse reverse output (not the number can also):

1 list = [1,2,3,4,5,6]2list.reverse ()3print(list)

Nesting:

LIST[A][B] The B element in the a element in the list.

1List = ['Taibai','Enrique','Yuanhao',['Alex','Egon', 89],23]2 3 Print(list[1][1])4Name =List[0].capitalize () capitalize the element with position 05LIST[2] ='Court Day Day' Replace the element with position 2 with the day of the garden
6LIST[2] = Li[2].replace ('Hao','Ritian')     Change the position of 2 Hao this element to day
7 List[3][0] = Li[3][0].upper () capitalize the No. 0 element of the list with position 3

string did not change, can only be replaced. Note Use Replace.

2. Yuan zu

Ganso read-only list, can be circular query, can be sliced. A son cannot change, and his grandson can change.

You can think of a tuple as a list, but only the surface can not be changed, the next layer to do the operation.

1 tu = (the"Alex", [2,3,4,'taibai'],' Egon ')

The elements inside [2,3,4, ' Taibai '] can be modified. (List method can be used)

Join (an Iterative object) (is a string)

1 ' Alex ' 2 ' *** ' . Join (S) 3 Print (x) 4 result is: a***l***e***x

string - list split!!!

list - string join!!!

Range(A,b, step) interval, do not take the last one,ifa is equal to 0 , then do not write.

Range is a list containing numbers [1,2,3,4,5 ...]

can be taken backwards (the tail Head - the step size)

Interview questions, there are pits. Range(0,ten,-1) No output or error

1  for  in range (3,10):2     print(i)3 result is 3 4 5 6 7 8 9

1  for  in range (0,10,3):2     print(i)3 result is 0 3 6 9

1  for  in range (10,0,-2):2     print(i)3 result is 10 8 6 4 2

1  for  in range (10,-1,-2):2     print(i)3 result is 10 8 6 4 2 0

A notation for the most basic elements of an output (nested)

1Li = [1,2,3,5,'Alex', [2,3,4,5,'Taibai'],'AfDs']2  forIinchLi:3     ifType (i) = =list:4          forJinchI:5             Print(j)6         Continue7     Print(i)

Python Day-4