Create Lists Of Unique Names In A For -loop In Python

I want to create a series of lists with unique names inside a for-loop and use the index to create the liste names. Here is what I want to do x = [100,2,300,4,75] for i in x: l

Solution 1:

Don't make dynamically named variables. It makes it hard to program with them. Instead, use a dict:

x = [100,2,300,4,75]
dct = {}
for i in x:
    dct['lst_%s' % i] = []

print(dct)
# {'lst_300': [], 'lst_75': [], 'lst_100': [], 'lst_2': [], 'lst_4': []}

Solution 2:

Use a dictionary to hold your lists:

In [8]: x = [100,2,300,4,75]

In [9]: {i:[] for i in x}
Out[9]: {2: [], 4: [], 75: [], 100: [], 300: []}

To access each list:

In [10]: d = {i:[] for i in x}

In [11]: d[75]
Out[11]: []

And if you really want to have lst_ in each label:

In [13]: {'lst_{}'.format(i):[] for i in x}
Out[13]: {'lst_100': [], 'lst_2': [], 'lst_300': [], 'lst_4': [], 'lst_75': []}

Solution 3:

A slight variation to the other's dict-solutions is to use a defaultdict. It allows you to skip the initialisation step by invoking the chosen type's default value.

In this case the chosen type is a list, which will give you empty lists in the dictionary:

>>>from collections import defaultdict>>>d = defaultdict(list)>>>d[100]
[]