Question

python 列表中删除 部分一些符合条件的值

list=[None,None,None,None,"a","b","c",None,"d",12,None,2,4,5,4]
1. 我要删除前面四个None, 后面的两个None需要保留
2. 数从"a"到最后 4 之间一共几值. (包括中间的两个"None")

Answer 1

>>> list =[None,None,None,None,"a","b","c",None,"d",12,None,2,4,5,4]
>>> list = list[4:]
>>> len(list)
11
>>> list
['a', 'b', 'c', None, 'd', 12, None, 2, 4, 5, 4]
>>>
#如果你的list 格式是相同的 比如前面4个都是None，这个格式是固定的，那么切片很容易解决

追问

问题就是要确定前面有几个None.. 谢谢

追答

tmp = []
list =[None,None,None,None,None,"a","b","c",None,"d",12,None,2,4,5,4]
for i,v in enumerate(list): 
    if not v:
        continue
    else:
        tmp = list[i:]
        break
print tmp
#list 前面是连续的None， 都可以删除

Answer 2

>>> list=[None,None,None,None,"a","b","c",None,"d",12,None,2,4,5,4]
>>> n=len(list[:-11])
>>> n
4
这个就能算出来a前面有几个None

Answer 3

应该是符合的