CODEWITHSUNDEEP
python
KLAUS
KLAUS

Reputation: 31

Data Structure to store a Table values in python

REFERENCE What can be the most efficient way to store and retrieve this type of table.

Product Category Original Price Discount(%)
First Stationary 1000 10
Second Clothing 2000 5 
stationary_items =[]
stationary_items.append({"Product" : "NOTEBOOK", "Category" : "STATIONARY", "Price" : 200, "Discount" : 20})
stationary_items.append({"Product" : "PENS", "Category" : "STATIONARY", "Price" : 300, "Discount" : 10})
stationary_items.append({"Product" : "MARKERS", "Category" : "STATIONARY", "Price" : 500, "Discount" : 5})


clothing_items = []
clothing_items.append({"Product" : "TSHIRT", "Category" : "CLOTHING", "Price" : 1000, "Discount" : 10})
clothing_items.append({"Product" : "JACKET", "Category" : "CLOTHING", "Price" : 2000, "Discount" : 5})
clothing_items.append({"Product" : "CAP", "Category" : "CLOTHING", "Price" : 500, "Discount" : 20})

I have to make queries later like if product is notebook then do something edit : I cannot use 3rd party libraries,

Upvotes: 1

Views: 164

Answers (1)

zok
zok

Reputation: 176

Consider using NamedTuple since you have a fixed set of keys (table headers).

You can use one-line factory:

Point = namedtuple('Point', ['x', 'y'])

or a class-like definition with type-hints:

class Employee(NamedTuple):
    name: str
    id: int

Both of this approaches gives your a nice hints for defined attributes and allows you to not pay hashing costs.

If you have a list of such namedtuples, than you can filter it like [item for item in clothing_items if item.category == 'clothing' and product == 'tshirt'], it returns you a list of matching items.

You can describe a custom collection class, to store items hierarchically. smth like that (suppose that Product is namedtuple describing a table row):

class ProductsByCategory:
    def __init__(self):
        self._products_by_category_map: dict[str, list[Product]] = defaultdict(list)
    
    def add(product: Product):
        self._products_by_category_map[product.category].append(product)

    def __getitem__(self, category) -> [Product]:
        return self._products_by_category_map[category]

Then list of products related to 'clothing' category may be accessed like products_by_category['clothing'].

With this approach you can go further and make it "product by product name map by category map", also you can control in add method that there is only unique pairs of category and product name, so product_by_name_by_category['clothing']['tshirt'] may return you exactly one Product instance, instead of list of Product instances, so you can access it's .discount field directly.

Keep in mind possibility of KeyError while accessing products.

Upvotes: 1

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