一入python深似海--list
几个实例展示python中数据结构list的魅力！
list变量申明
the_count = [1, 2, 3, 4, 5] fruits = ['apples', 'oranges', 'pears', 'apricots'] change = [1, 'pennies', 2, 'dimes', 3, 'quarters']
访问list元素
array= [1,2,5,3,6,8,4] #其实这里的顺序标识是 (0，1，2，3，4，5，6) (-7,-6,-5,-4,-3,-2,-1)#有负的下标哦 array[0:]#列出index==0以后的 [1,2,5,3,6,8,4] array[1:]#列出index==1以后的 [2,5,3,6,8,4] array[:-1]#列出index==-1之前的 [1,2,5,3,6,8] array[3:-3]#列出index==3到index==-3之间的,<span style="color:#ff0000;">注意不包含index==-3，即左闭右开</span> [3]
list应用
loops and list
change = [1, 'pennies', 2, 'dimes', 3, 'quarters']
for i in change:
print "I got %r" % i
enumerate
for i,j in enumerate([[1,2],['o',2],[9,3]]): k1,k2=j print i,k1,k2
output
0 1 2 1 o 2 2 9 3
append/extend/pop/del
append()添加元素至list尾部
elements=[1,2,3,4,5] elements.append(6)
extend()拼接两个list
list1=[1,2,3,4,5] list2=[6,7] elements.extend(list2) print elements
pop(int i=-1)删除list中指定下标的元素，并返回该位置上的数，default ：删除最后一个
elements=[1,2,3,4,5] print elements.pop()#default:delete index==-1,i.e. the last element print elements elements=[1,2,3,4,5] elements.pop(-2)#delete index==-2,i.e. 4 print elements elements.pop(1) print elements
del
elements=[1,2,3,4,5] del elements[0]#default:delete index==0,i.e. 1 print elements elements=[1,2,3,4,5] del elements[2:4]#delete index==2 and index==3,i.e.3 and 4 print elements elements=[1,2,3,4,5] del elements#delete all elements
do things to list
ten_things = "Apples Oranges Crows Telephone Light Sugar"
print "Wait there's not 10 things in that list, let's fix that."
stuff = ten_things.split(' ')
more_stuff = ["Day", "Night", "Song", "Frisbee", "Corn", "Banana", "Girl", "Boy"]
while len(stuff) != 10:
next_one = more_stuff.pop()
print "Adding: ", next_one
stuff.append(next_one)
print "There's %d items now." % len(stuff)
print "There we go: ", stuff
print "Let's do some things with stuff."
print stuff[1]
print stuff[-1] # whoa! fancy
print stuff.pop()
print ' '.join(stuff) # what? cool!
print '#'.join(stuff[3:5]) # super stellar! outputs:stuff[3]#stuff[4]
' '.join(things) reads as, "Join things with ' ' between them." Meanwhile, join(' ', things) means, "Call join with ' ' and things。返回一个string.
输出
Wait there's not 10 things in that list, let's fix that. Adding: Boy There's 7 items now. Adding: Girl There's 8 items now. Adding: Banana There's 9 items now. Adding: Corn There's 10 items now. There we go: ['Apples', 'Oranges', 'Crows', 'Telephone', 'Light', 'Sugar', 'Boy', 'Girl', 'Banana', 'Corn'] Let's do some things with stuff. Oranges Corn Banana ['Apples', 'Oranges', 'Crows', 'Telephone', 'Light', 'Sugar', 'Boy', 'Girl', 'Corn'] Apples Oranges Crows Telephone Light Sugar Boy Girl Corn Telephone#Light#Sugar
实验一些list的方法：
>>>n1=[1,2,3,4]
>>>print nl.count(5) # 计数，看总共有多少个5
>>>print nl.index(3) # 查询 nl 的第一个3的下标
>>>nl.append(6) # 在 nl 的最后增添一个新元素6
>>>nl.sort() # 对nl的元素排序
>>>print nl.pop() # 从nl中去除最后一个元素，并将该元素返回。
>>>nl.remove(2) # 从nl中去除第一个2
>>>nl.insert(0,9) # 在下标为0的位置插入9