List contents erasing themselves once exiting the function definition

Question

I have created a dictionary called sol:

sol = {'Uranus': [2750, 3000, 2880], 'Mercury': [46, 70, 57], 'Earth': [147, 152, 150], 'Venus': [107, 109, 108], 'Mars': [205, 249, 228], 'Saturn': [1350, 1510, 1430], 'Jupiter': [741, 817, 779], 'Neptune': [4450, 4550, 4500], 'Pluto': [4440, 7380, 5910]}

And using a data file STATUS_FILE1:

Mars,True
Mercury,True
Neptune,True
Uranus,True
Earth,True
Venus,True
Pluto,False
Jupiter,True
Saturn,True

I have built the following list in the following to have the list run parallel with the dictionary in order.

def load_status(sol, status):
    with open(STATUS_FILE1, "r") as s:      #Opens data file
        for line in s:
            line = line.rstrip('\n')
            if len(line) > 0:
                k, v = line.split(',')
                if k in sol:
                    sol[k].append(v)             #Matches key with T/F value and adds to dictionary
    status = [v[-1] for k, v in sol.items()]     # Populates status list in correct order based on dict
    for k, v in sol.items():                     # Removes unneeded T/F from dictionary
        v.pop()
    booleans = []                                # Converts string to boolean terms
    for v in status:
        if v == "True":
            booleans.append(True)
        else:
            booleans.append(False)
    status = booleans                           # Final list converted
    print(status)

So this prints exactly what I want:

[True, True, True, True, True, True, True, True, False]

However, even if I use a return function, in the main() function the status[] list is empty. Even if I remove the v.pop and boolean conversion it still prints a blank list. I've moved it around, and I am stumped and frustrated due to completing the function just to have it fail. Any ideas would be appreciated.

As requested, the status will then be used in the following format:

print("The list of all planets is:", planets_list(sol, status))

This function uses the status as shown here:

idx = 0
for planet in planets:
    if stat[idx]:
        pl.append(planet)
    idx += 1

Answer 1

Inside your load_status you're discarding the status parameter, building a new list, and then not returning it to the caller. Since you ignore the status that the caller passed you, it shouldn't be a parameter in the first place, and should instead be the return value that you give back to the caller (i.e. it should be the output, rather than the input, of the function).

---

At the beginning of load_status, change:

def load_status(sol, status):

to:

def load_status(sol):

Then at the end of load_status, change:

print(status)

to:

return status

Then in your main() function, change:

# you can delete whatever created status too
load_status(sol, status)

to:

status = load_status(sol)
print(status)

Now you still get the list printed out, but it's also available as a variable called status in the body of main().