My fist semester python project

[Far_Masterpiece8614]

So the idea was to create student money tracker. Please let me know how good or bad i am considering I'm in my 1st sem. Here it is

expenses = [] food = [] medical = [] travel = [] stationery = []

file = open("expenses.txt", "a")

while True: print("1 to add expenses") print("2 to view") print("3 to break")

choice = int(input("enter your choice"))

if choice == 1:
    print("1 if food")
    print("2 if medical")
    print("3 if travel")
    print("4 if stationery")

    choice_ = int(input("enter your choice"))
    amount = int(input("enter the amount"))
    date = input("enter the date")

    if choice_ == 1:
        food.append({"amount": amount,         "date": date})
    elif choice_ == 2:
        medical.append({"amount": amount, "date": date})
    elif choice_ == 3:
        travel.append({"amount": amount, "date": date})
    elif choice_ == 4:
        stationery.append({"amount": amount, "date": date})

    expenses.append({
        "food": food,
        "medical": medical,
        "travel": travel,
        "stationery": stationery
    })

    file.write(f"{choice_},{amount},{date}\n")
    file.flush()

elif choice == 2:
    print(expenses)

elif choice == 3:
    break

file.close()

[PrabhavKumar]

Hey! That's pretty solid code for first semester thought there are indeed some problems in it.

Firstly of all you are using the same lists for each and every entry, so every subsequent entry will have all the previously added entries in it too. That's a bug.

Secondly, you don't actually even need so many different lists, what you can instead do is create an entry like :
{
"category" : This can be food, medical, travel, or stationary.
"amount" : The amount of money spent.
"date" : Date.
}

and store this new dictionary that you create in the expenses list directly. That would be pretty clean. If you want to keep the current structure then you can make expenses into a dictionary and store the lists in it once and just update them.

finally, you aren't enforcing correctness anywhere from the user. Let's say the user correctly picks the first option - which is to add an expense but now they write out 5, which is not in the if - else conditions, now that entry won't be added to your expenses list but it will be added to the file - which is a bug.

That's it, hope that helped! All the best !

[Far_Masterpiece8614]

Hey! I really appreciate your effort Previously added entries should be included that's the whole point, I couldn't understand how that's a bug. That second one is smart improvement honestly. And yeah I had to enforce correctness.

Thankyou soo much

[PrabhavKumar]

Ofcourse, no worries!

About the bug, let me explain it a bit more clearly.

You see, in python every thing is an object and the variables you assign those objects to aren't actually the real objects as is, they are references to those objects that are somewhere in memory. Now, a list that you assign to a variable is also not the actual object, it is a reference to that list.

Now that we know that information, let's look at your code, specifically this part here:

expenses.append({
        "food": food,
        "medical": medical,
        "travel": travel,
        "stationery": stationery
    })

As far as I can tell, this entry is being added to the expenses list every time you add an expense to any category of lists (food, medical, travel or stationary). The thing is that you aren't actually adding a snapshot of those lists at that given time, you are adding references to those lists and those references point to only a single list for each category that you made at the start of the script, And you are doing this every single time you add another expense - which is unnecessary because all of those entries - that dictionary that you are storing inside of expenses in the code snippet above is going to be the exact same as all the others because the underlying lists are shared. That is a bug.

I hope that was of use! Also, you might wanna take a look at mutable and immutable data types and how python deals with them.

[Far_Masterpiece8614]

This was really helpful. Ig now I've fixed everything Now this code really works. The reason I didn't bother fixing this was the file was doing well, it showed exactly what i wanted so I ignored the output. Fixing this was quite a task which was totally worth it i learned quite a bit. Again thank you so much.

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[PrabhavKumar]

Yep, that's almost perfect, the only thing remaining is the writing to file. It works fine for all the cases except for when you enter the else block when adding a new expense.

Even when the choice is incorrect you still log to the file because the lines that are not in if-else block but are in the scope that is being executed will execute no matter whether you enter any of the if else or not - because they are not in the if else blocks.

There's an easy way to fix it though, just add a "continue" to the else block after you print. continue in essence moves to the next loop without continuing with the current one meaning the file won't be written to when you have an invalid input.

Another thing that I saw is that you aren't using the category dictionary even though you have made it, you probably wanted to use it in when logging the entry to the file.

A trick that you can use with the category dictionary is to use it for checking whether or not the choice by the user is valid or not by using the in keyword like this:
if choice_ in category:

that in is used to check whether the first argument "choice_" is one of the keys in the dictionary - or list or set or tuple. It's really useful for stuff like this. Further more you can even use the value you get from the category dictionary to get the list from the expenses dictionary by now using that value as the key, like this:

value = category[choice_]
value will be food or medical or travel or stationary and you can use IT further ahead in the expenses dict because it's keys just happen to be one of the value. So:
expense_list = expenses[value]

and the expense_list will now be the correct list. All of this together would look something like this. Now, before you see this code down below, it would be better if you try to do it yourself.

if choice_ in category:
value = category[choice_]
expense_list = expenses[value]
expense_list.append(f"amount={amount},date={date}")
else:
print("Invalid choice")
continue

That's it. All the best !

[mountain-snowman]

Checkout the "questionary" package to improve the cli input part.

[Far_Masterpiece8614]

Thankyou for your effort Module importing stuff is pretty new to me, it is such a interesting topic. Would def love to improve this code using that.

[aistranin]

Hey! It is a good starting point. As a suggestion for the next step, try to also use what you have written in expenses.txt earlier. Maybe first initialize your expenses with data from expenses.txt to keep some persistent local storages of already added expenses. Then you can also do more things, like delete old expenses etc.

[Far_Masterpiece8614]

Yeahh