Python中的列表知识点汇总

>>> l = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> type(l)
<type 'list'>
>>> el = []  # Create an empty list
>>> len(el)
0
>>> sl = [1]  # Create a single item list
>>> len(sl)
1
>>> sl = [1,]  # Create 
a single item list, as with a tuple
>>> len(sl)
1

>>> help(list)
Help on class list in module __builtin__:
class list(object)
 | list() -> new list
 | list(sequence) -> new list initialized from sequence's items
 | 
 | Methods defined here:
 | 
 | __add__(...)
 |   x.__add__(y) <==> x+y
 | 
 | __contains__(...)
 |   x.__contains__(y) <==> y in x
 | 
...

>>> l = list()
>>> type(l)
<type 'list'>
>>> len(l)
0
>>> l
[]
>>> l = list((0, 1, 2, 3, 4, 5, 6, 7, 
8, 9))  # Create a list from a tuple
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> len(l)
10
>>> l = list([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])  # Create a list from a list
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> len(l)
10
>>> l = list(0, 1, 2, 3, 4, 5, 6, 7, 
8, 9)   # Error: Must pass in a sequence
Traceback (most recent call last):
 File "<stdin>", line 1, in ?
TypeError: list() takes at most 1 argument (10 given)
>>> l = list("0123456789") # Create a list from a string
>>> l
['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
>>> type(l)
<type 'list'>
>>> len(l)
10

>>> l = list([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> l[0]     # Get the first item in the list
0
>>> type(l[0])
<type 'int'>
>>> l[5]     # Get the sixth item in the list
5
>>> l[1:5]    # Get the second through fifth items
[1, 2, 3, 4]
>>> type(l[1:5])
<type 'list'>
>>> l[0::2]   # Get every second item 
[0, 2, 4, 6, 8]
>>> l[0], l[1], l[2]  
(0, 1, 2)

>>> l = []
>>> l[0] = 0   # The list is empty
Traceback (most recent call last):
 File "<stdin>", line 1, in ?
IndexError: list assignment index out of range
>>> l.append(0)
>>> l
[0]
>>> l[0] = 1
>>> l
[1]

>>> l=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> l[2] = 2
>>> type(l[2])
<type 'int'>
>>> l[2] = "two"   # Change the type of an element
>>> ,ype(l[2])
<type 'str'>
>>> l
[0, 1, 'two', 3, 4, 5, 6, 7, 8, 9]
>>> l[2] = l[2:5] * 2 
>>> l
[0, 1, ['two', 3, 4, 'two', 3, 4], 3, 4, 5, 6, 7, 8, 9]
>>> del(l[2])     # Remove single element
>>> l
[0, 1, 3, 4, 5, 6, 7, 8, 9]
>>> l[1:3] = []    # Remove a slice
>>> l 
[0, 4, 5, 6, 7, 8, 9]

>>> al = [[0, 1, 2], [3, 4, 5], [6, 7, 8]]
>>> al
[[0, 1, 2], [3, 4, 5], [6, 7, 8]]
>>> al[0][0]     # First element in 2D array
0
>>> al[2][2]     # Last element in 2D array
8
>>> al[1][2]
5
>>> al = [[[0, 1], [2, 3]], [[4, 5], [6, 7]]]
>>> al
[[[0, 1], [2, 3]], [[4, 5], [6, 7]]]
>>> al[0][0][1]
1
>>> len(al)      # Length of outer dimension
2
>>> len(al[0])    # Length of middle dimension
2
>>> len(al[0][0])   # Length of inner dimension
2

>>> l=[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> id(l) # This is the object id for our current list
4525432
>>> l.reverse()    # Reverse the list
>>> l
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
>>> id(l) # The id is the same, modified list in place.
4525432
>>> l.sort()     # Sort the list in numerical order
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> id(l) # Modified the existing list
4525432
>>> l.index(5)    # Same as l[5]
5
>>> l.count(0)    # How 
many times does '0' occur in the list
1
>>> l.pop()      # Take off the last item (Stack)
9
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8]
>>> l.pop(5)     # Take out the fifth element
5
>>> l
[0, 1, 2, 3, 4, 6, 7, 8]
>>> l.pop(0)     # Take the first item off the list (Queue)
0
>>> l
[1, 2, 3, 4, 6, 7, 8]