Not sure if anyone can help. This is my first class so I'm very new to python and programming in general. I have a program for my Python class that I am stuck on. I have it doing the basics, but cannot figure out how to check the inventory quantity against the user inputted quantity. I know the nested if statement is incorrect ( I left that in so I had something) but that's what I'm struggling with.
Also..I have only laid out the ending part of the program which is why my input is blank.
supplier_data is what was provided to us by the instructor.
supplier_data = '{"parts": ["sprocket", "gizmo", "widget", "dodad"], "sprocket":
{"price": 3.99, "quantity": 32}, "gizmo": {"price": 7.98, "quantity": 2}, "widget":
{"price": 14.32, "quantity": 4}, "dodad": {"price": 0.5, "quantity": 0}}'
import json
json.loads(supplier_data)
new_data = json.loads(supplier_data)
print(new_data)
print("Welcome to the parts ordering system, please enter in a part name, followed
by a quantity.\n")
print("Parts for order are:\n")
print("sprocket")
print("gizmo")
print("widget")
print("dodad\n\n")
order = {}
inventory = True
while inventory:
part_input = input("Please enter in a part name, or quit to exit: ")
if part_input in new_data.keys():
quantity_input = int(input("Please enter in a quantity to order: "))
order[part_input] = quantity_input
print(order)
if quantity_input >= new_data['sprocket']['quantity']:
print("Error, only" new_data['sprocket']['quantity'] part_input "
are available!")
continue
elif part_input == "quit":
inventory = False
else:
print("Error, part does not exist, try again.")
This is what I get currently when I run it.
Welcome to the parts ordering system, please enter in a part name, followed by a quantity.
Parts for order are:
sprocket
gizmo
widget
dodad
Please enter in a part name, or quit to exit: sprocket
Please enter in a quantity to order: 3
{'sprocket': 3}
Please enter in a part name, or quit to exit: gizmo
Please enter in a quantity to order: 1
{'sprocket': 3, 'gizmo': 1}
Please enter in a part name, or quit to exit: widget
Please enter in a quantity to order: 8
{'sprocket': 3, 'gizmo': 1, 'widget': 8}
Please enter in a part name, or quit to exit: dodad
Please enter in a quantity to order: 1
{'sprocket': 3, 'gizmo': 1, 'widget': 8, 'dodad': 1}
Please enter in a part name, or quit to exit: quit
Your Order
Total: $
Thank you for using the parts ordering system!
Process finished with exit code 0
CodePudding user response：
The error I see is in the line
if quantity_input >= new_data['sprocket']['quantity']:
print("Error, only" new_data['sprocket']['quantity'] part_input "
are available!")
Replace the first key with part_input
This should be more like this
if quantity_input >= new_data[part_input]['quantity']:
print("Error, only" new_data[part_input]['quantity'] part_input "
are available!")
And just for user-friendliness just add this line inside your first if
print(f'{part_input} has quantity {supplier_data_dict[part_input]["quantity"]}')
Also, you have a logic error since your dictionary has 'parts' as another key. I can tell that it should not be regarded as a part type. I hope it helps
CodePudding user response：
Here's a solution that also performs the discount of each order's quantity from supplier data, whenever an order is placed:
import json
import pprint
supplier_data = """{"parts": ["sprocket", "gizmo", "widget", "dodad"],
"sprocket": {"price": 3.99, "quantity": 32}, "gizmo": {"price": 7.98, "quantity": 2},
"widget": {"price": 14.32, "quantity": 4}, "dodad": {"price": 0.5, "quantity": 0}}"""
json.loads(supplier_data)
new_data = json.loads(supplier_data)
print(f"{' Inventory Program ':=^50}")
print(
"Welcome to the parts ordering system, please enter in a part name, "
"followed "
"by a quantity.\n"
)
print(
"Parts to order can be one of:\n- "
"\n- ".join(new_data["parts"])
"\n\n"
)
order = {}
inventory = True
while inventory:
total_parts_left = sum(
value.get("quantity", 0) if isinstance(value, dict) else 0
for value in new_data.values()
)
if total_parts_left <= 0:
pprint.pprint(
"There are no more quantities left for any part. Exiting..."
)
inventory = False
break
part_input = input(
"Please enter a part name, or quit/q to exit\nAvailable parts:\n- "
"\n- ".join(
filter(lambda key: new_data[key]["quantity"] > 0, new_data["parts"])
)
"\n\nPart name:"
)
if part_input in new_data.keys():
quantity_input = int(
input(
f"Please enter in a quantity to order ("
f"{new_data[part_input]['quantity']:,} units available):"
)
)
if quantity_input > new_data[part_input]["quantity"]:
print(
f"Error: only {new_data[part_input]['quantity']} units are "
f"available for {part_input}!"
)
continue
else:
order[part_input] = order.get(part_input, 0) quantity_input
print(
f'\nYour order of {quantity_input:,} units for part "'
f'{part_input}" was fullfilled!\n'
)
pprint.pprint("Updated order:")
pprint.pprint(order)
print("\n" "=" * 50 "\n")
# Note: comment the next line if you don't want to update the
# `supplier_data`
# inventory of each part, after an order gets placed.
new_data[part_input]["quantity"] -= quantity_input
elif part_input in ["quit", "q"]:
inventory = False
else:
print(
f'Error: part "{part_input}" does not exist, choose one of the '
f"following:\n- "
"\n- ".join(new_data["parts"])
"\n\nThen try again..."
)
order_cost = sum(
new_data[key]["price"] * value if isinstance(new_data[key], dict) else 0
for key, value in order.items()
)
if order_cost > 0:
print(f"\n{' Your Order ':=^50}")
pprint.pprint(order)
print(f"Total Cost: ${order_cost:,.2f}")
else:
print("You didn't order any part...")
Output Example:
"""
=============== Inventory Program ================
Welcome to the parts ordering system, please enter in a part name, followed by a quantity.
Parts to order can be one of:
- sprocket
- gizmo
- widget
- dodad
Please enter a part name, or quit/q to exit
Available parts:
- sprocket
- gizmo
- widget
Part name: sprocket
Please enter in a quantity to order (32 units available): 32
Your order of 32 units for part "sprocket" was fullfilled!
'Updated order:'
{'sprocket': 32}
==================================================
Please enter a part name, or quit/q to exit
Available parts:
- gizmo
- widget
Part name: gizmo
Please enter in a quantity to order (2 units available): 2
Your order of 2 units for part "gizmo" was fullfilled!
'Updated order:'
{'gizmo': 2, 'sprocket': 32}
==================================================
Please enter a part name, or quit/q to exit
Available parts:
- widget
Part name: widget
Please enter in a quantity to order (4 units available): 5
Error: only 4 units are available for widget!
Please enter a part name, or quit/q to exit
Available parts:
- widget
Part name: widget
Please enter in a quantity to order (4 units available): 4
Your order of 4 units for part "widget" was fullfilled!
'Updated order:'
{'gizmo': 2, 'sprocket': 32, 'widget': 4}
==================================================
'There are no more quantities left for any part. Exiting...'
=================== Your Order ===================
{'gizmo': 2, 'sprocket': 32, 'widget': 4}
Total Cost: $200.92
"""
Commented Solution
Here's a commented version of the solution:
import json
import pprint
# 1. First, we load the `supplier_data` into a dictionary using `json.loads()`.
# The loaded dictionary will be stored inside a variable named `new_data`
supplier_data = """{"parts": ["sprocket", "gizmo", "widget", "dodad"],
"sprocket": {"price": 3.99, "quantity": 32}, "gizmo": {"price": 7.98, "quantity": 2},
"widget": {"price": 14.32, "quantity": 4}, "dodad": {"price": 0.5, "quantity": 0}}"""
json.loads(supplier_data)
new_data = json.loads(supplier_data)
print(f"{' Inventory Program ':=^50}")
print(
"Welcome to the parts ordering system, please enter in a part name, "
"followed "
"by a quantity.\n"
)
print(
"Parts to order can be one of:\n- "
"\n- ".join(new_data["parts"])
"\n\n"
)
order = {}
inventory = True
# 2. Then, we create a `while` loop that will keep running until the user
# decides to quit.
while inventory:
# 3. Calculate the total number of parts left in the inventory.
# If there aren't any parts left, print a message to notify the user and
# exit the `while` loop.
total_parts_left = sum(
value. Get("quantity", 0) if isinstance(value, dict) else 0
for value in new_data.values()
)
# 4. If the total number of parts left is less than or equal to 0, we print
# a message and exit the program.
if total_parts_left <= 0:
pprint.pprint(
"There are no more quantities left for any part. Exiting..."
)
inventory = False
break
# 5. If the total number of parts left is greater than 0, we ask the user
# to enter a part name. The `filter` statement allows us to print the
# parts that have a quantity greater than 0 left.
part_input = input(
"Please enter a part name, or quit/q to exit\nAvailable parts:\n- "
"\n- ".join(
filter(lambda key: new_data[key]["quantity"] > 0, new_data["parts"])
)
"\n\nPart name:"
)
# 6. If the part name entered by the user is in the `supplier_data`
# dictionary, we ask the user to enter a quantity.
if part_input in new_data.keys():
quantity_input = int(
input(
f"Please enter in a quantity to order ("
f"{new_data[part_input]['quantity']:,} units available):"
)
)
# 7. If the quantity entered by the user is greater than the quantity
# available for that part, we print an error message and ask the user
# to enter a part name again.
if quantity_input > new_data[part_input]["quantity"]:
print(
f"Error: only {new_data[part_input]['quantity']} units are "
f"available for {part_input}!"
)
continue
# 8. If the quantity entered by the user is less than or equal to the
# quantity available for that part, we add the part and quantity
# to the `order` dictionary, print the updated order, and update the
# quantity available for that part in the `supplier_data` dictionary.
else:
order[part_input] = order.get(part_input, 0) quantity_input
print(
f'\nYour order of {quantity_input:,} units for part "'
f'{part_input}" was fullfilled!\n'
)
pprint.pprint("Updated order:")
pprint.pprint(order)
print("\n" "=" * 50 "\n")
# Note: comment the next line if you don't want to update the
# `supplier_data`
# inventory of each part, after an order gets placed.
new_data[part_input]["quantity"] -= quantity_input
# 9. If the user enters `quit` or `q`, we exit the `while` loop.
elif part_input in ["quit", "q"]:
inventory = False
# 10. If the part name entered by the user is not in the `supplier_data`
# dictionary, we print an error message and ask the user to enter a part
# name again.
else:
print(
f'Error: part "{part_input}" does not exist, choose one of the '
f"following:\n- "
"\n- ".join(new_data["parts"])
"\n\nThen try again..."
)
# 11. After the `while` loop, we calculate the total cost of the order.
order_cost = sum(
new_data[key]["price"] * value if isinstance(new_data[key], dict) else 0
for key, value in order.items()
)
# 12. If the total cost of the order is greater than 0, we print the order
# and the total cost. Total cost only equals zero if no quantity for any
# part is specified.
if order_cost > 0:
print(f"\n{' Your Order ':=^50}")
pprint.pprint(order)
print(f"Total Cost: ${order_cost:,.2f}")
# 13. If the total cost of the order is less than or equal to 0, meaning no
# order was placed, we print a message saying that the user didn't
# order any part.
else:
print("You didn't order any part...")