How to group a list of Locations

Question

I have this list of WorldTime with keys, How do I group these list by the location key. Below is the code i have written.

List<WorldTime> locations = [
    WorldTime(url: 'Europe/London', location: 'London', flag: 'London.png'),
    WorldTime(url: 'Africa/Abidjan',location:'Abidjan'),
    WorldTime(url: 'Africa/Accra', location: 'Accra', flag: 'ghana.png'),
    WorldTime(url: 'Africa/Algeria', location: 'Algiers', flag: 'Algeria.png'),
    WorldTime(url: 'Africa/Guinea ', location: 'Bassau', flag: 'Guinea'),
    WorldTime(url: 'Africa/Cairo', location: 'Cairo', flag: 'Egypt.png'),
    WorldTime(url: 'Africa/Casablanca', location: 'Casablanca', flag: 'Casablanca.png'),
    WorldTime(url: 'Africa/Ceuta ', location: 'Ceuta', flag: 'Ceuta.png'),
    WorldTime(url: 'Africa/El_Aaiun', location: 'El_Aaiun', flag: 'El_Aaiun'),
    WorldTime(url: 'Africa/Johannesburg', location: 'Johannesburg', flag: 'Johannesburg.png'),
    WorldTime(url: 'Africa/Juba', location: 'Juba', flag: 'Juba.png'),
    WorldTime(url: 'Africa/Khartoum', location: 'Khartoum', flag: 'Khartoum.png'),
    WorldTime(url: 'Africa/Lagos', location: 'Lagos', flag: 'Lagos.png'),
    WorldTime(url: 'Africa/Maputo', location: 'Maputo', flag: 'Maputo.png'),
    WorldTime(url: 'Africa/Monrovia', location: 'Monrovia', flag: 'Monrovia.png'),
    WorldTime(url: 'Africa/Nairobi', location: 'Nairobi', flag: 'Nairobi.png'),
    WorldTime(url: 'Africa/Ndjamena', location: 'Ndjamena', flag: 'Ndjamena.png'),
```![End Result](https://i.stack.imgur.com/DVPHK.png)

do you mean sort or group? group will make sense if location can be repeated. I don't see that here. — Taha Malik, Nov 23 '20 at 00:34
It is unclear exactly what you are trying to do based on your question. Please provide a description/example of the result you expect from this "grouping"? — Lee3, Nov 23 '20 at 04:15
Does this answer your question? [Flutter/Dart how to groupBy list of maps](https://stackoverflow.com/questions/54029370/flutter-dart-how-to-groupby-list-of-maps) — Taha Malik, Nov 23 '20 at 08:59

Luiz Filipe Medeira · Answer 1 · 2020-11-23T09:53:02.850

Dart collections does not have a group function like Kotlin, but you can use this lib: https://pub.dev/packages/supercharged

Now you can group:

List<WorldTime> locations = [
WorldTime(url: 'Europe/London', location: 'London', flag: 'London.png'),
WorldTime(url: 'Africa/Abidjan',location:'London'),
WorldTime(url: 'Africa/Accra', location: 'Accra', flag: 'ghana.png'),
WorldTime(url: 'Africa/Algeria', location: 'Algiers', flag: 'Algeria.png'),
]

locations.groupBy((element) => element.location == 'London' ? "currentLocation" : "otherLocations")

score 0 · Answer 2 · answered Nov 23 '20 at 00:40

0

I'm assuming you want to sort the list by location? (Sorry your question is a little confusing)

You can use the List.sort() function, it would look like this:

locations.sort((a,b) => a.location.compareTo(b.location));
print(locations)

answered Nov 23 '20 at 00:40

Jackson Lee

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4
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its group not sort – Godwin Alexander Ekainu Nov 23 '20 at 01:03
@G-Codes Why would you group when items are unique? – Jackson Lee Nov 23 '20 at 01:07
this is the problem I have, is there a way around it? because some locations like America having various cities with different time zones can't be left alone. I need to group them under America – Godwin Alexander Ekainu Nov 23 '20 at 01:17
America would be the Continent, the locations being cities would still be unique wouldn't it? Could you give an example? – Jackson Lee Nov 23 '20 at 02:26

How to group a list of Locations

2 Answers2