Keywords
in
Use the in keyword to check if a value is present in a variable or data structure. For example, checking if a product ID exists in a dictionary.
products_dict = {'OS31': 20, 'HT91': 15, 'MX01': 30}
print('OS31' in products_dict) # Check if OS31 is a key in the dictionary
Output:
True
This prints True because OS31 is a key in the dictionary.
not
The not keyword helps confirm that a value is not in a data structure.
print('OS31' not in products_dict) # Check if OS31 is not a key
Output:
False
It prints False because OS31 is a key in the dictionary.
and
The and keyword allows us to check if multiple conditions are met at once.
print('HT91' in products_dict and min(products_dict.values()) > 5)
Output:
True
It checks if both conditions are true: "HT91" is a key, and the minimum price is more than 5.
or
The or keyword checks if at least one of several conditions is true.
print('HT91' in products_dict or min(products_dict.values()) < 5)
Output:
True
It prints True because "HT91" is a key in the dictionary, even though the minimum price is above 5.
Update Variables
We can modify variables within loops using operators like += or -=.
stock = 10
stock -= 1 # Decrease stock by 1
print(stock)
Output:
9
The stock is decreased by 1 and the updated value is printed.
Store Values in a List
You can append values that meet certain conditions to a list.
product_ids = []
for product, price in products_dict.items():
if price >= 20:
product_ids.append(product)
print(product_ids)
Output:
['OS31', 'MX01']
This code appends product IDs where the price is at least 20 to a list, and the result shows OS31 and MX01 as meeting the condition.