Creating a description of an item from an inventory

Question

I'm really new to Python (like only a month of study) and I was testing out dictionaries, so I tried to make an 'inventory' where you can pick an item from your inventory and examine it. But I can tell that I'm not doing this in the most efficient or elegant way.

Originally I thought I could make each item its separate dictionary, kind of like this:

#define what's in your inventory using a list
inventory = ["apple", "tire"]
#create a list of items with attributes using dictionaries
apple = {
 "name":"apple",
 "type":"fruit",
 "edible":"edible",
 "color":"red",
}
tire = {
 "name":"tire",
 "type":"object",
 "edible":"not edible",
 "color":"grey"
}
#explain the program to the user
print("Choose an item to examine. Items in your inventory are:")
print(*inventory, sep = ", ")
#set the loop to true
itemsloop = True
#begin the loop
while itemsloop == True:
 #ask for user input
 x = input()

But then I got stuck at the part where it's time to take the input and match it to the name of a dictionary, because one is a string and one isn't. The following code is working, but feels... inelegant and unnecessary to type out (prefix)-name, (prefix)-type, (prefix)-edible for every entry. I feel like there must be a simpler way to accomplish this that I'm just not seeing because I don't think like a programmer yet. I don't know.

If you can explain any more efficient methods with simple terminology (again, huge newbie not just to Python but programming in general), I'd really appreciate it!

#define what's in your inventory using a list
inventory = ["apple", "tire"]
#create a list of items with attributes using a dictionary
items = {
 "apple-name":"apple",
 "apple-type":"fruit",
 "apple-edible":"edible",
 "apple-color":"red",
 "tire-name":"tire",
 "tire-type":"object",
 "tire-edible":"not edible",
 "tire-color":"grey"
}
#explain the program to the user
print("Choose an item to examine. Items in your inventory are:")
print(*inventory, sep = ", ")
#set the loop to true
itemsloop = True
#begin the loop
while itemsloop == True:
 #ask for user input
 x = input()
 if x in inventory:
 #if the input matches something you have, find the attributes of
 #the item in the inventory and print them.
 print("This is a " + items[x + "-color"] + " " + 
 items[x + "-name"] + ", a type of " + items[x + "-type"] 
 + ". It is " + items[x + "-edible"] + ".")
 elif x == "quit":
 #if the player wishes to quit, end the program.
 itemsloop == False
 break
 else:
 #if the item is not recognized, let the player know.
 print("You don't have that in your inventory.")

(The sample output would be something like, "This is a red apple, a type of fruit. It is edible.")

Answer 1

To expand on the answer given by @Aries_is_there in, you should indeed make your dictionary a nested dictionary with the item names as first keys and the item properties as keys of the sub dictionaries.

You should also be aware that x in inventory is \$\mathcal{O}(n)\$ if inventory is a list, but this is mitigated when making it a dictionary, because x in items is \$\mathcal{O}(1)\$ for dictionaries.

Your printing can also be simplified by using an f-string.

I would also add a if __name__ == "__main__" guard to allow importing functions form this script from another script.

And finally, Python has an official style-guide, PEP8, which is well worth a read. You are already mostly following it, except for the missing spaces after the : in your dictionaries.

items = {"apple": {"name": "apple",
 "type": "fruit",
 "edible": "edible",
 "color": "red"},
 "tire": {"name":"tire",
 "type":"object",
 "edible":"not edible",
 "color":"grey"}}
if __name__ == "__main__":
 print("Choose an item to examine. Items in your inventory are:")
 print(*items.keys(), sep = ", ")
 while True:
 x = input()
 if x in inventory:
 #if the input matches something you have, find the attributes of
 #the item in the inventory and print them.
 item = items[x]
 print(f"This is a {item['color']} {item['name']}, a type of {item['type']}. It is {item['edible']}.")
 elif x == "quit":
 #if the player wishes to quit, end the program.
 break
 else:
 #if the item is not recognized, let the player know.
 print("You don't have that in your inventory.")

You could take it one level further by making it object-oriented. In this case you would probably want an Object class for which you define the magic __str__ method, which controls what happens if you do print(x).

class Object:
 def __init__(self, name, type="object", edible=False, color=None):
 self.name = name
 self.type = type
 self.edible = edible
 self.color = color
 def __str__(self):
 s = ["This is a "]
 if self.color is not None:
 s.append(self.color + " ")
 s.extend([self.name, f", a type of {self.type}."]
 s.append(f"It is {'not ' if not self.edible else ''}edible.")
 return "".join(s)
items = {"apple": Object("apple", "fruit", edible=True, color="red"),
 "tire": Object("tire", color="grey")}
if __name__ == "__main__":
 print("Choose an item to examine. Items in your inventory are:")
 print(*items.keys(), sep = ", ")
 while True:
 x = input()
 if x in items:
 #if the input matches something you have, find the attributes of
 #the item in the inventory and print them.
 item = 
 print(items[x])
 elif x == "quit":
 #if the player wishes to quit, end the program.
 break
 else:
 #if the item is not recognized, let the player know.
 print("You don't have that in your inventory.")

• Red: Thank you very much for the thorough explanation. I didn't know you could nest dictionaries! I'm still new to a lot of the things included in your post, so i will be doing googling for a while, haha. Do you have any recommendations on a good newbie explanation for magic methods? I had never heard of those.

Answer 2

As you use item's name to search the item information, so you can design the name as the key of items hash table.

items = {
 "apple":
 {
 #type, edible,color information
 },
 ...
}

• Red: I didn't understand that you could use dictionaries as dictionary keys. Thank you.
• Aries_is_there: haha as long as you get @Graipher answer, he did a good explain
• Graipher: @Red You actually can't. But you can use them as dictionary values. If you want to use them as keys you would have to convert the dictionary into a tuple of key, value tuples first, so it is hashable. This would be sensitive to the order then, though.