Python: Determine whether list of lists contains a defined sequence
- by duhaime
I have a list of sublists, and I want to see if any of the integer values from the first sublist plus one are contained in the second sublist. For all such values, I want to see if that value plus one is contained in the third sublist, and so on, proceeding in this fashion across all sublists. If there is a way of proceeding in this fashion from the first sublist to the last sublist, I wish to return True; otherwise I wish to return False. In other words, for each value in sublist one, for each "step" in a "walk" across all sublists read left to right, if that value + n (where n = number of steps taken) is contained in the current sublist, the function should return True; otherwise it should return False. (Sorry for the clumsy phrasing--I'm not sure how to clean up my language without using many more words.)
Here's what I wrote.
a = [ [1,3],[2,4],[3,5],[6],[7] ]
def find_list_traversing_walk(l):
for i in l[0]:
index_position = 0
first_pass = 1
walking_current_path = 1
while walking_current_path == 1:
if first_pass == 1:
first_pass = 0
walking_value = i
if walking_value+1 in l[index_position + 1]:
index_position += 1
walking_value += 1
if index_position+1 == len(l):
print "There is a walk across the sublists for initial value ", walking_value - index_position
return True
else:
walking_current_path = 0
return False
print find_list_traversing_walk(a)
My question is: Have I overlooked something simple here, or will this function return True for all true positives and False for all true negatives? Are there easier ways to accomplish the intended task? I would be grateful for any feedback others can offer!
