如何将序列号附加到列表中

Question

例如： 我有一个像['a','b','c','d']的列表，我倾向于使用python2.7添加我的列表输出的序列号应该像：

[[1,'a'],[2,'b'],[3,'c'],[4,'d']]

我该怎么办（没有其他模块）？提前致谢！

我倾向于

a = ['a','b','c','d']
b = []
for i,item in enumerate(a,start=1):
c = b.append([i,item])
print c

但输出为None

Answer 1

>>> [[x, x] for x in [1, 2, 3, 4, 5]]
[[1, 1], [2, 2], [3, 3], [4, 4], [5, 5]]

Answer 2

>>> a = ['a','b','c','d']
>>> c = [[i+1, a[i]] for i in range(len(a))]
>>> c
[[1, 'a'], [2, 'b'], [3, 'c'], [4, 'd']]