Python Learning Note 4-list

List definition

>>> a=[' Free','1998']>>>type (a)<type'List'>>>> BOOL (a)#true if the list has a valueTrue>>>Printa[' Free','1998']>>>

Indexes and slices

 >>> a=[ " hello  , "  world  ,  '  2006   '   '  >>> a[1 '   '  world   '  >>> a[1:2< Span style= "color: #000000;" >][  " world    world   ' ] 

List function

>>>dir (list) ['__add__','__class__','__contains__','__delattr__','__delitem__','__delslice__','__doc__','__eq__','__format__','__ge__','__getattribute__','__getitem__','__getslice__','__gt__','__hash__','__iadd__','__imul__','__init__','__iter__','__le__','__len__','__lt__','__mul__','__ne__','__new__','__reduce__','__reduce_ex__','__repr__','__reversed__','__rmul__','__setattr__','__setitem__','__setslice__','__sizeof__','__str__','__subclasshook__','Append','Count','Extend','Index','Insert','Pop','Remove','Reverse','Sort']

Appand Append element

>>> fruits=[‘Orange‘,‘apple "" banana ' ]>>> fruits.append ( '  ' banana ' 

extend merging of two lists

>>> a=[1,2,3]>>> b=[4,5]>>> a.extend (b)>>> a[ 1, 2, 3, 4, 5]

Extend object is a list, if it is str, then Python will first convert it by character to list and then append to the known list

>>> La = [a]>>> B ="ABC">>>La.extend (b)>>>la[1, 2, 3,'a','b','C']>>> C = 5>>>La.extend (c) Traceback (most recent): File"<stdin>", Line 1,inch<module>TypeError:'int'Object is  notIterable

Reverse reversal

Method 1[::-1]

>>> a=[1,2,3]>>> a[::-1[3, 2, 1>>> a="python  ">>> a[::-1]'nohtyp'

Method 2:list (Reversed (list))

>>> a=[1,2,3]>>> list (reversed (a)) [3, 2, 1]

Method 3:reverse

>>> a=[1,2,3]>>> a.reverse ()>>> a[3, 2, 1]

Count counts the number of occurrences of an element in a list and returns 0 if none

>>> c=[a,b,c,a,a]>>> c.count (a)3
>>> C.count (' F ')
0

Index to return indexes

>>> c=[a,b,c,a,a]>>> c.index (a)         #第一次出现的位置0

Insert

The I in List.insert (i, x) is the position where the element x is inserted into the list, and the x is inserted in front of the element where the index value is i. Note that the index is from 0

>>> l=['a','b','C','D']>>> L.insert (1,'#')>>>l['a','#','b','C','D']

If I is greater than the maximum value of the index, then it becomes an append

>>> a = [A.insert]>>> 9,777 >>> a[1, 2, 3, 777]

Remove

Remove the first matching element

>>> lst=['a','b','a','C']>>> Lst.remove ('a')>>>lst['b','a','C']

Pop

To remove an element from an index

>>> lst=['a','b','a','C']>>>lst.pop (0)'a'>>>lst['b','a','C']

Sort

By default, a small-to-large sort is implemented.

>>> lst=[4,5,7,1,9]>>> lst.sort ()>>> lst[1, 4, 5, 7, 9]

From big to small

>>> lst=[4,5,7,1,9]>>> lst.sort (reverse=True)>>> lst[9, 7, 5, 4, 1]

Sort by keyword

>>> LST = ["Python","Java","C","Pascal","Basic"]>>> Lst.sort (key=len)>>>lst['C','Java','Basic','Python','Pascal']

Python Learning Note 4-list