Splitting a list into new lists

Question

So I have a list plaintextthat contains ['A', 'A', 'R', 'O', 'N'] and I want to end up with a set of lists called letter1, letter2, letter3, and so on, that contain ['A'], ['A'], ['R'], and so on. How do I go about doing this without cloning the list five times and removing the extra parts?

Answer 1

You can iterate over the list:

In [1]: letters = ['A', 'A', 'R', 'O', 'N']

#use list comprehension to iterate over the list and place each element into a list
In [2]: [[l] for l in letters]
Out[2]: [['A'], ['A'], ['R'], ['O'], ['N']]

To add titles, we typically use a dictionary. For example

#create a dictionary
letters_dict = {}

#iterate over original list as above except now saving to a dictionary
for i in range(len(letters)):
    letters_dict['letter'+str(i+1)] = [letters[i]]

This gives you the following:

In [4]: letters_dict
Out[4]:
{'letter1': ['A'],
 'letter2': ['A'],
 'letter3': ['R'],
 'letter4': ['O'],
 'letter5': ['N']}

You can now access each of the lists as follows:

In [5]: letters_dict['letters1']
Out[5]: ['A']

Finally, just for completeness, there's a cool extension of the dictionary method. Namely, using code from this thread, you can do the following:

#create a class
class atdict(dict):
    __getattr__= dict.__getitem__
    __setattr__= dict.__setitem__
    __delattr__= dict.__delitem__ 

#create an instance of the class using our dictionary:
l = atdict(letters_dict)

This way, you can do the following:

In [11]: l.letter1
Out[11]: ['A']

In [12]: l.letter5
Out[12]: ['N']

If you have no desire to store the values in an iterable or referencable object (ie dictionary, list, class) as you suggest in your question, then you could literally do the below:

letter1 = letters[0]
letter2 = letters[1]
letter3 = letters[2]
#and so forth ...

but as you can see, even with 6 variables the above becomes tedious.