Compiling a nested list with conditional statement

Question

I want to create a nested list with one or more of the below lists of tuples, with the order of the list based on user's preference.

Fruits=[("Apples",2),("Oranges",3),("Pineapples",5)]
Clothes=[("Jeans",10),("Shirts",5),("Dresses",15)]
Pets=[("Dogs",3),("Cats",4),("Turtles",2)]

The order of the nested list will depend on the preference of the user.For instance, if the user prefer pets over clothes over fruits. The list will look like this:

[[("Jeans",10),("Shirts",5),("Dresses",15)],[("Jeans",10),("Shirts",5), 
("Dresses",15)],[("Apples",2),("Oranges",3),("Pineapples",5)]]

The user also have the option of picking only one or two items. For instance, if the user only cares about pet and then clothing (doesn't care about fruits), his/her list will look like this.

[[("Dogs",3),("Cats",4),("Turtles",2)],[("Jeans",10),("Shirts",5), 
("Dresses",15)]]

The user input is a list with the preferences in order. For example:

preference= ["Pets", "Fruits", "Clothing"] # preference list for users who care about pets over fruits over clothing.
            or 
preference= ["Fruits", "Clothing"] # preference list for users who care about fruits over clothing (no regard for pets)

This is how I've tried to tackle the problem. First I create an empty list with a corresponding number of nested list:

empty_list=[[] for x in range (len(preferences)]

This creates a place holder for the number of nested list I need. I then run a bunch of conditional statement to pop in one list at the time:

if preference[0]=="Fruits":
    empty_list[0]=Fruits
    if preference[1]=="Clothes":
        empty_list[1]=Clothes
        empty_list[2]=Pets
   elif preference[1]=="Pets":
        empty_list[1]=Pets
        empty_list[2]=Clothes

if preference[0]=="Pets":
    empty_list[0]=Pets
    if preference[1]=="Clothes":
        empty_list[1]=Clothes
        empty_list[2]=Fruits
    elif preference[1]=="Fruits":
        empty_list[1]=Fruits
        empty_list[2]=Clothes

if preference[0]=="Clothes":
    empty_list[0]=Clothes
    if preference[1]=="Pets":
        empty_list[1]=Pets
        empty_list[2]=Fruits
    elif preference[1]=="Fruits":
        empty_list[1]=Fruits
        empty_list[2]=Pets

My solution is inefficient and also causes problem with list assignment out of range if there are only two preference as opposed to three. Is there a more Pythonic way of writing this?

Any tip or guidance is most appreciated.

Joran Beasley · Accepted Answer · 2018-11-14 00:24:39Z

1

you should store your data in a dictionary

and then access that dictionary by key

data = dict(
    Fruits=[("Apples",2),("Oranges",3),("Pineapples",5)]
    Clothes=[("Jeans",10),("Shirts",5),("Dresses",15)]
    Pets=[("Dogs",3),("Cats",4),("Turtles",2)]
)

once you have it in a dict you can easily access the values with variables

fruits = "Fruits"
my_fruits = data[fruits]

you can then use a simple list comprehension to capture all of your interests

interests = ["Fruits","Pets"]    
interesting_things = [data[interest] for interest in interests]

interests = ["Fruits","Clothes"]
interesting_things = [data[interest] for interest in interests]

edited Nov 14, 2018 at 0:24

answered Nov 14, 2018 at 0:13

Joran Beasley

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Comments

Baryon · Accepted Answer · 2018-11-14 00:22:26Z

0

Try this method.

def prefer(preference):
    preference_list = []

    choices = {
        "fruits": [
            ("Apples", 2),
            ("Oranges", 3),
            ("Pineapples", 5)
        ],
        "cloths": [
            ("Jeans", 10),
            ("Shirts", 5),
            ("Dresses", 15)
        ],
        "pets": [
            ("Dogs", 3),
            ("Cats", 4),
            ("Turtles", 2)
        ]
    }

    for choice in choices:
        if choice in preference:
            preference_list.insert(preference.index(choice), choices[choice])

        else:
            preference_list.append(choices[choice])


    print(preference_list)

prefer(("fruits", "cloths"))

answered Nov 14, 2018 at 0:22

Baryon

10811 bronze badges

1 Comment

sangurocactus Over a year ago

This works great. Thank you! The only change I had to make was getting rid of the preference_list.append (choices[choice]) as the number of preference list can be fewer than 3.

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