Append is overwriting existing dictionary in list

Question

I’m pretty new to python, and I have a python program that is supposed to take inputs and store them into a dictionary and store that dictionary into a list, but for some reason, it’s overwriting the stored dictionary in the list with the new one at each loop.

total_properties_sold = 0
total_commission = 0
bonus_pay = 0
employees = [] #empty list to store dictonary of employees information
employee = {} #empty dictonary to store the information of employees

while True:
    number_of_employees = input("Enter number of employees who have worked this week: ")
    if number_of_employees.isdigit(): #validation check to ensure input is a digit
        number_of_employees = int(number_of_employees) #if input is digit, convert to int
        if number_of_employees >= 2 and number_of_employees <= 5: #validates the range of input
            break
        else:
            print("Input invalid... enter a digitn")
            
    else:
        print("Input invalid... enter a digitn")
        

#for loop to enter the details of the number of employees
for number in range(number_of_employees):
    name = input("Enter employee name: ")

    while True: #validation check to ensure input is a digit
        id = input("Enter employee id: ")
        if id.isdigit():
            id = int(id)
            break
        else:    
            print("Invalid data type... enter a numbern")

    while True:
        properties_sold = input("enter number of properties sold by employee: ")
        if properties_sold.isdigit():
            properties_sold = int(properties_sold)
            break
        else: 
            print("Invalid data type... enter a number")

    total_properties_sold += properties_sold #calculates the total properties sold this week
    employee_commission = properties_sold * 500 
    employee_commission = float(employee_commission) #converts commission into a float
    total_commission += employee_commission #calculates the total commission this week
    total_commission = float(total_commission) #converts total commission into float

    #add employee information into the employee dictonary
    employee["name"] = name
    employee["employee id"] = id
    employee["properties sold"] = properties_sold
    employee["commission"] = employee_commission

    employees.append(employee) #adding the employee dictonary into employees list
    
    print(employees)

The expected output should be

[{'name': 'employee1', 'employee id': 1, 'properties sold': 4, 'commission': 2000.0}, {'name': 'employee2', 'employee id': 2, 'properties sold': 3, 'commission': 1500.0}, {'name': 'employee3', 'employee id': 3, 'properties sold': 10, 'commission': 5000.0}]

But I get:

[{'name': 'employee3', 'employee id': 3, 'properties sold': 10, 'commission': 5000.0}, {'name': 'employee3', 'employee id': 3, 'properties sold': 10, 'commission': 5000.0}, {'name': 'employee3', 'employee id': 3, 'properties sold': 10, 'commission': 5000.0}]
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Asked By: Rohail

||

Source

Answer 1

This is because you assign employee = {} at the beginning of the code, and it is never reassigned after that, so the code is always referring to the same object.

When you set employee["name"] = name for the next employee, you’re still referring to the same employee object, and it affects the instance of employee that is already in the list.

To fix this, assign employee to a fresh dictionary at the top of the for loop:

for number in range(number_of_employees):
    employee = {}
    name = input("Enter employee name: ")

This reassigns the variable name employee to a fresh value, and breaks the connection to the previous values.

Answered By: John Gordon

Append is overwriting existing dictionary in list

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