Counting depth or the deepest level a nested list goes to
Solution 1
Breadth-first, without recursion, and it also works with other sequence types:
from collections import Sequence
from itertools import chain, count
def depth(seq):
for level in count():
if not seq:
return level
seq = list(chain.from_iterable(s for s in seq if isinstance(s, Sequence)))
The same idea, but with much less memory consumption:
from collections import Sequence
from itertools import chain, count
def depth(seq):
seq = iter(seq)
try:
for level in count():
seq = chain([next(seq)], seq)
seq = chain.from_iterable(s for s in seq if isinstance(s, Sequence))
except StopIteration:
return level
Solution 2
Here is one way to write the function
depth = lambda L: isinstance(L, list) and max(map(depth, L))+1
I think the idea you are missing is to use max()
Solution 3
Let's first rephrase your requirements slightly.
The depth of a list is one more than the maximum depth of its sub-lists.
Now, this can be translated directly to code:
def depth(l):
if isinstance(l, list):
return 1 + max(depth(item) for item in l)
else:
return 0
Solution 4
easy with recursion
def flat(l):
depths = []
for item in l:
if isinstance(item, list):
depths.append(flat(item))
if len(depths) > 0:
return 1 + max(depths)
return 1
Solution 5
Abusive way:
Say your list is called mylist
mybrackets = map(lambda x: 1 if x=='[' else -1, [x for x in str(mylist) if x=='[' or x==']'])
maxdepth = max([sum(mybrackets[:i+1]) for i in range(len(mybrackets))])
This converts your list to a list of opening and closing brackets, then finds the largest number of opening brackets that occur before the corresponding closing bracket occurs.
dhcarmona
Updated on January 02, 2022Comments
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dhcarmona over 2 years
A have a real problem (and a headache) with an assignment...
I'm in an introductory programming class, and I have to write a function that, given a list, will return the "maximum" depth it goes to... For example: [1,2,3] will return 1, [1,[2,3]] will return 2...
I've written this piece of code (it's the best I could get T_T)
def flat(l): count=0 for item in l: if isinstance(item,list): count+= flat(item) return count+1
However, It obviously doens't work like it should, because if there are lists that do not count for the maximum deepness, it still raises the counter...
For example: when I use the function with [1,2,[3,4],5,[6],7] it should return 2, but it returns 3...
Any ideas or help would be greatly appreciated ^^ thanks a lot!! I've been strugling with this for weeks now...