Map list from dictionaries

IIUC you could use simple list comprehension for that:

[dictionary[key] for key in list_to_be_mapped]

In [51]: [dictionary[key] for key in list_to_be_mapped]
Out[51]: [1, 1, 2, 6, 6, 1]

If you prefer pandas solution you could convert your list_to_be_mapped to Series and then use the same as in your example:

s = pd.Series(list_to_be_mapped)

In [53]: s
Out[53]:
0    a
1    a
2    b
3    c
4    c
5    a
dtype: object

In [55]: s.map(dictionary).tolist()
Out[55]: [1, 1, 2, 6, 6, 1]   

You can use the dictionary's get function

list(map(dictionary.get, list_to_be_mapped))