Python 在列表中查找一项，并将列表中的下一项更改为'；RD#u PUNC'；

我的代码是：

for i in range(0,len(mylist1)):    

        dot=str(i)+'.'
        print dot , mylist1[i]
        if dot in mylist1:
            print "find"
            mylist1[i+1]='RD_PUNC'
mylist1=['1.alen','N_NN','2.','N_NP','3.abr','N_NNP','4.london','N_NST','5.','N_NNP']  

我想找到2,4.，任何后跟“.”的数字，并将列表中的下一项更改为“RD_PUNC”。
我期望的输出是：

mylist1=['1.alen','N_NN','2.','RD_PUNC','3.abr','N_NNP','4.london','N_NST','5.','RD_PUNC']  

使用itertools：

from itertools import izip
import re
mylist1=['1.alen','N_NN','2.','RD_PUNC','3.abr','N_NNP','4.london','N_NST','5.','RD_PUNC']  
newList = []
def pairwise(iterable):
    a = iter(iterable)
    return izip(a, a)

replaceX = False
for x, y in pairwise(mylist1):
    if replaceX:
        x = 'RD_PUNC'
        replaceX = False
    elif re.match(r'\d+\.$', x):
        y = 'RD_PUNC'
    if re.match(r'\d+\.$', y):
        replaceX = True
    newList.append(x)
    newList.append(y)

print newList

输出：

['1.alen', 'N_NN', '2.', 'RD_PUNC', '3.abr', 'N_NNP', '4.london', 'N_NST', '5.', 'RD_PUNC']