given a list of transaction objects that contain coin name,datetime,profit earned/loss. write a function in dart that returns the top three coins with the highest average profit and the top 3 coins with highest average loss.
user
here's a function in dart that achieves this task:
```dart
import 'dart:collection';

// sample transaction data
list<transaction> transactions = [
  transaction('btc', now(), 50),
  transaction('btc', now().add(duration(days: 1)), -20),
  transaction('eth', now(), 30),
  transaction('eth', now().add(duration(days: 1)), -10),
  transaction('ltc', now(), 20),
  transaction('ltc', now().add(duration(days: 1)), 5),
];

class transaction {
  final string coin;
  final datetime time;
  final int profit;

  transaction(this.coin, this.time, this.profit);
}

map<string, transactionprofit> calculateprofit(list<transaction> transactions) {
  var transactionprofits = {};

  for (var transaction in transactions) {
    var coin = transaction.coin;
    transactionprofits.putifabsent(
      coin,
      () => transactionprofit(transaction),
    );
    transactionprofits[coin].addtransaction(transaction);
  }

  return transactionprofits;
}

class transactionprofit {
  final list<transaction> transactions;
  int totalprofit = 0;

  transactionprofit(this.transactions);

  void addtransaction(transaction transaction) {
    totalprofit += transaction.profit;
  }

  int get averageprofit => totalprofit ~/ transactions.length;
}

void main() {
  map<string, transactionprofit> profitmap = calculateprofit(transactions);

  list<string> top3highestprofit = gettop3highestprofit(profitmap);
  list<string> top3highestloss = gettop3highestloss(profitmap);

  print('top 3 coins with highest average profit:');
  for (string coin in top3highestprofit) {
    print('$coin: ${profitmap[coin].averageprofit}');
  }

  print('\ntop 3 coins with highest average loss:');
  for (string coin in top3highestloss) {
    print('$coin: ${-profitmap[coin].averageprofit}');
  }
}

list<string> gettop3highestprofit(map<string, transactionprofit> profitmap) {
  list<string> top3highestprofitcoins = [
    'btc',
    'eth',
    'ltc',
  ];

  if (profitmap.isnotempty) {
    top3highestprofitcoins = profitmap.keys
        .map((coin) => coin)
        .sort((a, b) => profitmap[b].averageprofit - profitmap[a].averageprofit)
        .take(3);
  }
  return top3highestprofitcoins;
}

list<string> gettop3highestloss(map<string, transactionprofit> profitmap) {
  list<string> top3highestlosscoins = [
    'btc',
    'eth',
    'ltc',
  ];

  if (profitmap.isnotempty) {
    top3highestlosscoins = profitmap.keys
        .map((coin) => coin)
        .sort((a, b) => -profitmap[b].averageprofit + profitmap[a].averageprofit)
        .take(3);
  }
  return top3highestlosscoins;
}
```
this code defines the `calculateprofit` function to compute the total profit and average profit for each coin, and the `gettop3highestprofit` and `gettop3highestloss` functions to return the top 3 coins with the highest and lowest average profit, respectively. the main function demonstrates how to use these functions with a sample list of transactions.

please note that the solution assumes transactions for each coin and calculates the total and average profit for each.
assistant
Here's a function in Dart that achieves this task:
```dart
import 'dart:collection';

// Sample transaction data
List<Transaction> transactions = [
  Transaction('BTC', now(), 50),
  Transaction('BTC', now().add(Duration(days: 1)), -20),
  Transaction('ETH', now(), 30),
  Transaction('ETH', now().add(Duration(days: 1)), -10),
  Transaction('LTC', now(), 20),
  Transaction('LTC', now().add(Duration(days: 1)), 5),
];

class Transaction {
  final String coin;
  final DateTime time;
  final int profit;

  Transaction(this.coin, this.time, this.profit);
}

Map<String, TransactionProfit> calculateProfit(List<Transaction> transactions) {
  var transactionProfits = {};

  for (var transaction in transactions) {
    var coin = transaction.coin;
    transactionProfits.putIfAbsent(
      coin,
      () => TransactionProfit(transaction),
    );
    transactionProfits[coin].addTransaction(transaction);
  }

  return transactionProfits;
}

class TransactionProfit {
  final List<Transaction> transactions;
  int totalProfit = 0;

  TransactionProfit(this.transactions);

  void addTransaction(Transaction transaction) {
    totalProfit += transaction.profit;
  }

  int get averageProfit => totalProfit ~/ transactions.length;
}

void main() {
  Map<String, TransactionProfit> profitMap = calculateProfit(transactions);

  List<String> top3HighestProfit = getTop3HighestProfit(profitMap);
  List<String> top3HighestLoss = getTop3HighestLoss(profitMap);

  print('Top 3 coins with highest average profit:');
  for (String coin in top3HighestProfit) {
    print('$coin: ${profitMap[coin].averageProfit}');
  }

  print('\nTop 3 coins with highest average loss:');
  for (String coin in top3HighestLoss) {
    print('$coin: ${-profitMap[coin].averageProfit}');
  }
}

List<String> getTop3HighestProfit(Map<String, TransactionProfit> profitMap) {
  List<String> top3HighestProfitCoins = [
    'BTC',
    'ETH',
    'LTC',
  ];

  if (profitMap.isNotEmpty) {
    top3HighestProfitCoins = profitMap.keys
        .map((coin) => coin)
        .sort((a, b) => profitMap[b].averageProfit - profitMap[a].averageProfit)
        .take(3);
  }
  return top3HighestProfitCoins;
}

List<String> getTop3HighestLoss(Map<String, TransactionProfit> profitMap) {
  List<String> top3HighestLossCoins = [
    'BTC',
    'ETH',
    'LTC',
  ];

  if (profitMap.isNotEmpty) {
    top3HighestLossCoins = profitMap.keys
        .map((coin) => coin)
        .sort((a, b) => -profitMap[b].averageProfit + profitMap[a].averageProfit)
        .take(3);
  }
  return top3HighestLossCoins;
}
```
This code defines the `calculateProfit` function to compute the total profit and average profit for each coin, and the `getTop3HighestProfit` and `getTop3HighestLoss` functions to return the top 3 coins with the highest and lowest average profit, respectively. The main function demonstrates how to use these functions with a sample list of transactions.

Please note that the solution assumes transactions for each coin and calculates the total and average profit for each.
assistant