How do you take a list that has multiple same values but when you display the list you only show one of each unique value?

Question

Here is some sample code from my larger program where I am searching for countries where specific airlines fly. When I run the entire program it works fine but the countries are displayed like this:

Canada
USA
USA
Brazil
Russia
Russia
Brazil
Canada

Where I want it to display only:

USA
Brazil
Russia
Canada

def displayCountriesForAirline(airlineName, airportIDs, airportDict):
    print("Aiports serviced by", airlineName)
    for airportID in airportIDs:
        if airportID in airportDict:
            airportInfo = airportDict[airportID]
            print("\t", airportInfo[2])

If you don't care abuot duplicates or about the order, then you should not be using a `list` at all. Use a `set` instead. Or, if you really need the `list` for something else, create a `set` out of it just for the sake of printing. — zvone, Nov 25 '19 at 00:53
Now I read the code as well ;) You dont really have a list either, but a dictionary... — zvone, Nov 25 '19 at 00:55
Does this answer your question? [Get unique values from a list in python](https://stackoverflow.com/questions/12897374/get-unique-values-from-a-list-in-python) — neutrino_logic, Nov 25 '19 at 00:55

Eric Gong · Answer 1 · 2019-11-25T09:33:15.247

0

I think you can transfer the list to set by using set(list1).

edited Nov 25 '19 at 09:33

answered Nov 25 '19 at 00:58

Eric Gong

107
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Names in Python (and almost every programming language) are case-sensitive, so you cannot write `SET` in capital letters to do this. – kaya3 Nov 25 '19 at 02:40
@kaya3 Sorry for the mistake. – Eric Gong Nov 25 '19 at 09:33

score 0 · Answer 2 · answered Nov 25 '19 at 00:58

You can use set() for storing the country names - That way, you won't have duplicates in your output (I created some example data):

airlineName = 'My Airline'
airportIDs = [1, 1, 2, 3, 3, 4, 4]
airportDict = {
    1:['x', 'y', 'Canada'],
    2:['x', 'y', 'USA'],
    3:['x', 'y', 'Brazil'],
    4:['x', 'y', 'Russia'],
}

def displayCountriesForAirline(airlineName, airportIDs, airportDict):
    print("Aiports serviced by", airlineName)
    countries = {airportDict[airportID][2] for airportID in airportIDs if airportID in airportDict}
    for country in countries:
        print("\t", country)

displayCountriesForAirline(airlineName, airportIDs, airportDict)

Prints:

Aiports serviced by My Airline
     USA
     Russia
     Canada
     Brazil

score 0 · Answer 3 · answered Nov 25 '19 at 00:58

0

You can change the list to a set like this to remove duplicates:

data = ['Canada','USA','USA','Russia','Russia','Brazil','Canada']

new_data=list(set(data))

print(new_data)
#['Brazil', 'Canada', 'Russia', 'USA']

answered Nov 25 '19 at 00:58

oppressionslayer

6,942
2
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How do you take a list that has multiple same values but when you display the list you only show one of each unique value?

3 Answers3