CODEWITHSUNDEEP
python
user838744
user838744

Reputation: 63

Creating a new list for each for loop

I wish to create a new list each time a for loop runs

#Reading user input e.g. 10
lists = int(raw_input("How many lists do you want? "))
for p in range(0,pooled):
    #Here I want to create 10 new empty lists: list1, list2, list3 ...

Is there any smart way of doing this?

Thanks,

Kasper

Upvotes: 5

Views: 77866

Answers (4)

VirtualScooter
VirtualScooter

Reputation: 1888

To create our lists we generate names on the fly and assign them an empty list:

lists = int(input("How many lists do you want? "))
varname = 'list'
for i in range(lists):
    exec(f"{varname}{i} = []")
exec(f'print(f"list{lists-1} is", list{lists-1})')
# list9 is []

Upvotes: 1

Rusty Rob
Rusty Rob

Reputation: 17173

perhaps in your situation you could use a defaultdict?

>>> from collections import defaultdict
>>> m=defaultdict(list)
>>> m
defaultdict(<type 'list'>, {})
>>> for i in range(5):
...     len(m[i])
... 
0
0
0
0
0
>>> m
defaultdict(<type 'list'>, {0: [], 1: [], 2: [], 3: [], 4: []})

Upvotes: 1

Fred Foo
Fred Foo

Reputation: 363487

Use a list comprehension:

num_lists = int(raw_input("How many lists do you want? "))
lists = [[] for i in xrange(num_lists)]

Upvotes: 8

Peter Collingridge
Peter Collingridge

Reputation: 10969

The easiest way is to create a list of lists:

   num_lists = int(raw_input("How many lists do you want? "))
   lists = []
   for p in range(num_lists):
        lists.append([])

Then you can access, for example, list 3 with list[2], and the ith item of list 3 with list[2][i].

Upvotes: 5

Related Questions