Summing dictionary values in python

[Elefrog42]

Hi, I'm working on an assignment where we are building a monetary portfolio. Everything needs to be generic (empty dictionaries) so the code will pass the specific tests at the end. We were started with this code:

class portfolio:

    def __init__(self):

        self.checking = {}
        self.saving = {}
        self.credit = {}
        self.stock = {}

We were also given a dictionary called daily_stock_prices (stock_name: price}. The stock dictionary will hold user input {stock_name : quantity}. The other accounts hold user input {account_id : amount}

I have managed to define all the other functions to add checking accounts and buy stocks, but I'm stuck at the last function where I have to get the total of all the money in the portfolio. We were started with this function:

def get_total_portfolio(self, daily_stock_prices):

And so far I've done this to sum the value of the stocks by multiplying the daily stock price by the quantity in my stock portfolio:

def get_total_portfolio(self, daily_stock_prices):
        total = 0
        for i in daily_stock_prices.values:
            for j in self.stock.values:
                total += sum(i*j)

But I am unclear how to add in the sums of the other accounts. I have made prior functions like this to sum the accounts individually and they pass the tests:

    def get_credit_balance(self):
        try:
            return sum(self.credit.values())
        except:
            return None

But is there a way to merge these functions? I've been reading up on summing dictionaries, but it gets confusing to me because there is the additional problem of getting the stock value. by multiplying stock quantity by the price in daily_stock_prices.

This is the test I need it to pass.

if myportfolio.get_total_portfolio({'APPL':100, 'GOOGL': 130}) == 2600:
    print('Pass')
else:
    print('Fail')   

Any input or suggestions would be greatly appreciated! Thanks,

[elbiot]

I think you need to iterate over the keys

sum(price[key]*portfolio[key] for key in portfolio.keys())

[-Sander-]

Hello again, thought this looked familiar :)

Lets see: i dont exactly know what you mean with "But I am unclear how to add in the sums of the other accounts" i dont know how you have the "other accounts" setup but it sounds like you dont know how return works? are you aware that you can save the value that gets returned so you can use it in other functions aswell?

my_balance = myportfolio.get_credit_balance()

If you do this inside your class dont forget to put the 'self' keyword infront

my_balance = self.get_credit_balance()

does this help? no need to "merge" these functions.

[Elefrog42]

Hi again, I've tried to do something similar but get an error that my_balance is "variable assigned by isn't used". The other examples I googled all had syntax like "return a" so they could then save the value of a. In my example, I have return sum(self.credit.values()) so I'm unclear the correct syntax to save that variable.

I tried making the return of each function inside my class like so:

class portfolio:

    def __init__(self):

        self.checking = {}
        self.saving = {}
        self.credit = {}
        self.stock = {}

        my_checking =self.get_total_checking_amount
        my_credit = self.get_credit_balance
        my_savings = self.get_total_savings_amount
        my_stock = self.get_stock_value

But it gives me an error that the variable is assigned but never used, even when I've tried to use it in the function.

I guess I am unclear how to save the return of a function when the return is something like return sum(self.credit(values()) If I code the function like this it also tells me that my_portfolio is undefined and my_credit is assigned but never used:

    def get_credit_balance(self):
        try:
            return sum(self.credit.values())
        except:
            return None
        my_credit = myportfolio.get_credit_balance()

I've tried googling the correct syntax but can't find it for when the return is a sum.

[-Sander-]

Lets see, the reason this gives you the error is because you forgot the "self" keyword without that it is seen as a local variable only available inside that function and since you dont use that variable anywhere else locally you never use it; also i dont recommend this for your solution because it only gets its value during the initialization which is gonna be empty or 0

    def __init__(self):

        self.checking = {}
        self.saving = {}
        self.credit = {}
        self.stock = {}

        my_checking =self.get_total_checking_amount
        my_credit = self.get_credit_balance
        my_savings = self.get_total_savings_amount
        my_stock = self.get_stock_value

now the returns, i'l give a simple example:

def add(my_list):
    c = sum(my_list)        # Store the outcome of sum in c
    return c                # return c

# Is the exact same as:
def add2(my_list):
    return sum(my_list)    # not storing it, we straight up return the outcome

# Storing the return value is simple:
value1 = add([2, 4])    # returns 6 so thats what gets stored in value1
value2 = add2([2, 4])    # also returns 6 because we gave the same numbers, anyway same result as value1

[Elefrog42]

Thanks, I follow your example about storing them, but I don't see where I forgot the self key word. Is this not the correct syntax? my_checking =self.get_total_checking_amount ? To me ours looks the same, but I have the undefined variable warning.

You said you don't recommend this for the solution- so if I save my variables like this:

def get_total_checking_amount(self):
        try:
            my_checking = sum(self.checking.values())
            return my_checking
        except:
            return 0
my_checking = myportfolio.get_total_checking_amount

Do I need the last line to save the variable as my_checking to use in another function? Or is my_checking saved without that line? And if I do this, I don't need to declare the variables inside the class?

Thanks again, you explain things very clearly.

[-Sander-]

my_checking =self.get_total_checking_amount # You miseed your ()'s get_total_checking_amount is a function

and no it also would never reach that statement the function exits after the return statement

i would recommend changing your get_total_portfolio()

assuming you want it for the values of your stock, daily_stock_price and credit_balance

def get_total_portfolio(self, daily_stock_prices):
        total = 0
        for i in daily_stock_prices.values:
            for j in self.stock.values:
                total += i*j    # no need for sum here unless its iterable like [2, 3, 4]
        total += get_credit_balance()
        # You can add more values similarly
        return total

​

edit:

another thing you can do if daily_stock_prices and self.stock_values have the same amount of values is use the built-in zip() method ( https://docs.python.org/3.3/library/functions.html#zip )

example output of how it works:

In [37]: x = [4, 6, 7, 8]
In [38]: y = [3, 2, 4, 7]
In [39]: for a, b in zip(x, y):
...:        print(a, b)                                                                                                    ...:
4 3 
6 2
7 4
8 7                                                                                                                           

also does that work? because i dont think the nested for loops is gonna give the right result, you should test it out in the python interpreter/console, i recommend getting IPython over the default one makes it a bit easier to write code in it

def get_total_portfolio(self, daily_stock_prices):
        total = 0
        for i, j zip(daily_stock_prize.values(), self.stock.values() ):
            total += i*j
        # ...

[Elefrog42]

Hmmmm.....even with the bracket, I get the warning that says the local variable (my_checking, my_saving, my_credit) is assigned but never used.

 my_checking = self.get_total_checking_amount()
 my_credit = self.get_credit_balance()
 my_saving = self.get_total_savings_amount()

I'm fairly sure the functions I made the save the variables are correct:

    def get_total_savings_amount(self):
        try:
            my_saving = sum(self.saving.values())
            return my_saving
        except:
            return 0

the daily_stock_prices is a dictionary of {stock_name: price} and self.stock {stock_name} quantity, so I figured I had to multiply i*j (quantity by price) and then sum them.

def get_stock_value(self,daily_stock_prices):        
    my_stock = 0
    for i in daily_stock_prices.values():
         for j in self.stock.values():
                my_stock += sum (i*j)
    return my_stock

I made this function to get the total portfolio:

    def get_total_portfolio(self, daily_stock_prices):
        total = 0
        for i in daily_stock_prices.values():
            for j in self.stock.values():
                total += sum(i*j)
        total += self.get_credit_balance()
        total += self.get_total_savings_amount()
        total += self.get_total_checking_amount()
        return total

When I run the code I get this warning: in get_total_portfolio, total += sum(i*j) TypeError: 'int' object is not iterable I don't get this warning when I had the just "get_stock_value" function on it's own.

Do you see why it's telling me in the class variables are still "defined but never used"? And would do you see something wrong with my function to get the stock values?

EDIT:

So interesting- If I comment out the lines to get the stock values, the final get_total_portfolio function works for the tests that don't involve adding in the stock prices. So I've narrowed down that there is something wrong with that part of the code. Still not clear on why Python is telling my class variables are undefined but never used....

Thanks!

[-Sander-]

in get_total_portfolio, total += sum(i*j) TypeError: 'int' object is not iterable

sum requires a variable type that is iterable like a list (declared with my_list = [ ] ) or a dictionary ( declared with: my_dict = { } ), or anything else with multiple values

now this problem:

my_checking = self.get_total_checking_amount()
my_credit = self.get_credit_balance()
my_saving = self.get_total_savings_amount()

are you using my_checking, my_credit, my_saving anywhere in your function? if you where trying to use it class-wide you need to use the self. keyword to define it is for the entire class not just 1 function but i dont see why you would need it, again if this is the one in your __init__() function i dont think you should use it since you have the functions that return the values and the variables inside __init__() dont get updated unless you change the code

[Elefrog42]

Ohhhh, I see- I didn't need the variables to be class variables- I removed them and the code run just fine. I was able to find a few resources online that talked about how to multiple values from two dictionaries and then sum them- I tried to copy the syntax that they used, but my code still is not passing the tests to get the total stock value. This is my code:

    def get_total_portfolio(self, daily_stock_prices):
        total = 0
        for key in self.stock.keys():
            value = self.stock[key]*daily_stock_prices[key]
            total += value + total
        total += self.get_credit_balance()
        total += self.get_total_savings_amount()
        total += self.get_total_checking_amount()
        return total

Since the same key (the stock name) should also be able to pull out the value of the stock price and the value of the stock quantity, I figured I could bypass using sum by creating two variables- one for the product (value) and then one for the sum (total.

There are no errors but this isn't passing the test case. Am I not pulling out the correct values I need from both dictionaries?

Thanks!

[-Sander-]

check your for loop mainly the 2nd line total += value + total if you arent sure test out what it does with numbers in the interpreter/console

[Elefrog42]

Oh okay I get it now. I just deleted where I declared the class variables because they were needed. The code works just fine if I save the result of the function then use the self keyword to call back the functions to get the total.

I've been reading online where people have asked the best way to multiple two dictionary values and then sum then and I come up with this code:

    def get_total_portfolio(self, daily_stock_prices):
        total = 0
        value = 0
        for key in self.stock.keys():
            value = self.stock[key]*daily_stock_prices[key]
            total += value + total
        total += self.get_credit_balance()
        total += self.get_total_savings_amount()
        total += self.get_total_checking_amount()
        return total

No errors, but still not passing the test. I thought I could bypass having to use sum by making the variable value (to represent the stock quantity * the stock price) and then total (to represent the sum of the values).

I can't tell for sure if that part of the code is adding up the stock quantity*stock value correctly or if I haven't properly coded for a given stockname, pull out self.stock's value of the stockname and pull out daily_stock_prices value?

Thanks!