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Two Dictionaries and a Sum!

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  Two Dictionaries and a Sum! Bradley Wright <bradley.wright.biz@gmail.com> - 2013-05-17 21:19 -0700
    Re: Two Dictionaries and a Sum! Spacelee <fjctlzy@gmail.com> - 2013-05-18 12:30 +0800
    Re: Two Dictionaries and a Sum! nanobio <hektorlg@gmail.com> - 2013-05-17 22:20 -0700
    Re: Two Dictionaries and a Sum! nanobio <hektorlg@gmail.com> - 2013-05-17 22:22 -0700
    Re: Two Dictionaries and a Sum! Chris Angelico <rosuav@gmail.com> - 2013-05-18 15:10 +1000
    Re: Two Dictionaries and a Sum! Roy Smith <roy@panix.com> - 2013-05-18 09:22 -0400

#45490 — Two Dictionaries and a Sum!

Confusing subject for a confusing problem (to a novice like me of course!)
Thx for the help in advance folks

I have (2) dictionaries:

prices = {
    "banana": 4,
    "apple": 2,
    "orange": 1.5,
    "pear": 3
}
    
stock = {
    "banana": 6,
    "apple": 0,
    "orange": 32,
    "pear": 15
}

Here's my instructions:

consider this as an inventory and calculate the sum (thats 4*6 = 24 bananas!)

HERES MY CODE:

for key in prices:
    print prices[key]*stock[key]

HERES THE OUTPUT:

48.0
45
24
0

ISSUE:
I need to find a way to add all of those together...any pointers?

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#45491

[Multipart message — attachments visible in raw view] — view raw

for key in prices.keys():
    print prices[key]*stock[key]


On Sat, May 18, 2013 at 12:19 PM, Bradley Wright <
bradley.wright.biz@gmail.com> wrote:

> Confusing subject for a confusing problem (to a novice like me of course!)
> Thx for the help in advance folks
>
> I have (2) dictionaries:
>
> prices = {
>     "banana": 4,
>     "apple": 2,
>     "orange": 1.5,
>     "pear": 3
> }
>
> stock = {
>     "banana": 6,
>     "apple": 0,
>     "orange": 32,
>     "pear": 15
> }
>
> Here's my instructions:
>
> consider this as an inventory and calculate the sum (thats 4*6 = 24
> bananas!)
>
> HERES MY CODE:
>
> for key in prices:
>     print prices[key]*stock[key]
>
> HERES THE OUTPUT:
>
> 48.0
> 45
> 24
> 0
>
> ISSUE:
> I need to find a way to add all of those together...any pointers?
> --
> http://mail.python.org/mailman/listinfo/python-list
>



-- 
*Space Lee*

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#45493

total,amount=0,0
for key in prices.keys():
   price=prices[key]*stock[key]
   total+=price
   print "%s %s" % (price,total)

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#45494

total,amount=0,0
for key in prices.keys():
    amount=prices[key]*stock[key]
    total+=amount
    print "%s %s" % (amount,total)

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#45495

On Sat, May 18, 2013 at 2:19 PM, Bradley Wright
<bradley.wright.biz@gmail.com> wrote:
> Confusing subject for a confusing problem (to a novice like me of course!)
> Thx for the help in advance folks
>
> I have (2) dictionaries:
>
> prices = {
>     "banana": 4,
>     "apple": 2,
>     "orange": 1.5,
>     "pear": 3
> }
>
> stock = {
>     "banana": 6,
>     "apple": 0,
>     "orange": 32,
>     "pear": 15
> }
>
> Here's my instructions:
>
> consider this as an inventory and calculate the sum (thats 4*6 = 24 bananas!)

Let me reword your problem a little, maybe it'll be a bit clearer.
You're trying to calculate the total value of all stock on hand, eg
for insurance purposes. That's not 24 bananas, that's $24 of bananas.
And the part you want now is to get the total value of your entire
stock. Great! You're very close to there...

> HERES MY CODE:
>
> for key in prices:
>     print prices[key]*stock[key]
>
> ISSUE:
> I need to find a way to add all of those together...any pointers?

... you just need to accumulate a sum. Since this is almost certainly
homework, I won't give you the answer, but here are a few pointers:

* You'll need a single variable (I use the term sloppily, Python
doesn't actually have variables per se) which will collect the final
total.
* Inside your loop, you're currently printing out an int/float with
the value of the current item. Just add it onto your accumulator.
* Python will happily work with integers and floats together, so you
can just do what's obvious and it'll work.

See where that takes you. Have fun! :)

ChrisA

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#45507

In article <6012d69f-b65e-4d65-90c4-f04876853f5e@googlegroups.com>,
 Bradley Wright <bradley.wright.biz@gmail.com> wrote:

> Confusing subject for a confusing problem (to a novice like me of course!)
> Thx for the help in advance folks
> 
> I have (2) dictionaries:
> 
> prices = {
>     "banana": 4,
>     "apple": 2,
>     "orange": 1.5,
>     "pear": 3
> }
>     
> stock = {
>     "banana": 6,
>     "apple": 0,
>     "orange": 32,
>     "pear": 15
> }
> 
> Here's my instructions:

Hmmm, homework for a class?

> consider this as an inventory and calculate the sum (thats 4*6 = 24 bananas!)

I suspect what you're trying to say is that bananas cost BTC 4 each, and 
since you've got 6 bananas, you've got BTC 24 worth of bananas, yes?  
And now you want to find the total value of your fruit supply?

>> HERES MY CODE:
> 
> for key in prices:
>     print prices[key]*stock[key]
> 
> HERES THE OUTPUT:
> 
> 48.0
> 45
> 24
> 0

So far, so good.  A couple of things you may have noticed along the way:

1) Your orange unit price was a float, so the total value of all your 
oranges is a float as well.  That's how math works in Python.

2) The keys are presented in random order.  To make the output easier to 
interpret, you might want to do:

    print key, prices[key]*stock[key]


> ISSUE:
> I need to find a way to add all of those together...any pointers?

The most straight-forward way would be something like:

total = 0
for key in prices:
    fruit_subtotal = prices[key]*stock[key]
    total += fruit_subtotal
    print key, fruit_subtotal

print total


There are better ways to do this in Python, but start like this and get 
that to work.

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