dictionary in python problem

Question

problem.getSuccessors(getStartState()) - it returns something like ( (4,5) , north, 1) - that means 3 things - tuple, direction,cost.

I'm using a dictionary ,closed = {} Now I need to put the output of above function in the dictionary "closed" - how can I do that??

I need to use only dictionary because I need to return "action" i.e North, south....at the end of function. after doing some iterations, my dict is going to have multiple entries such as ((4,5),north,1) , ((3,4),south,1) and I need to extract the key from the dict i.e (4,5) .what shud I use?

Answer 1

I need to put the output of above function in the dictionary "closed" - how can I do that??

It entirely depends on what you want to use as the key, and what as the value! If the key is something completely unrelated to the tuple ( (4,5) , north, 1) (I'm not sure what the north identifier is supposed to be or how it got thee -- you sure it's not the string 'north' instead?!), then @mipadi's answer is correct. If the first item (the nested tuple) is the key, the other two the value, then, after

s = problem.getSuccessors(getStartState())

you'll do:

closed[s[0]] = s[1:]

If the "tuple and direction", together, are the key, and just the cost is the value, then you'll do, instead:

closed[s[:2]] = s[2]

So, what is it that you intend to use as the key into the dictionary closed?!

• Shilpa: I am going to use the (4,5) as the key and other 2 as values. so I shud do "s = problem.getSuccessors(getStartState())" closed[s[0]] = s[1:] If I need to use only the key, then wat shud I do? Because later on, closed to going to have a lot of entries like ((4,5),north,1).
• Shilpa: And ya if forget to mention,,it is 'north'. NOT north string
• Alex Martelli: If you "need to use only the key" (and never the value), then, use a set, not a dict (just make it with closedset=set() and add entries with closedset.add(s[0])!). If instead what you mean is that there are many direction-cost entries for each given value of the "tuple" (like (4, 5)), then import collections, use closed = collections.defaultdict(list), and closed[s[0]].append(s[1:]). If you could explain your needs with any clarity at all, helping you would be much, much easier (and I note you still haven't accepted my other answer you praised...).
• Shilpa: I need to use only dictionary because I need to return "action" i.e North, south....at the end of function. after doing some iterations, my dict is going to have multiple entries such as ((4,5),north,1) , ((3,4),south,1) and I need to extract the key from the dict i.e (4,5) .what shud I use?
• Shilpa: I always appreciate your response.You are the best.

Answer 2

closed = {}
# ...
closed["your_key"] = problem.getSuccessors(getStartState())

Responding to comment:

If by "take out" you mean you want (4,5) to be the key and (north, 1) to be the value, you can slice the tuple:

val = problem.getSuccessors(getStartState())
closed[val[0]] = val[1:]

If you just want to drop the (4,5), you can also slice the tuple:

closed["your_key"] = problem.getSuccessors(getStartState())[1:]

And yes, you can use a variable as a key instead of a hard-coded string.

• Shilpa: "your_key" can be any variable - like index What if I need to take out the first thing (4,5) from it, what are the commands I shud use then?