Performancefilter - improve sorting

Ordering of Pairs without history should remain identical, so pairs with
positive performance move to the front, and negative pairs move to the back.

closes #4893

freqtrade/plugins/pairlist/PerformanceFilter.py

@@ -60,6 +60,7 @@ class PerformanceFilter(IPairList):
 
         # Get pairlist from performance dataframe values
         list_df = pd.DataFrame({'pair': pairlist})
+        list_df['prior_idx'] = list_df.index
 
         # Set initial value for pairs with no trades to 0
         # Sort the list using:
@@ -67,7 +68,7 @@ class PerformanceFilter(IPairList):
         #  - then count (low to high, so as to favor same performance with fewer trades)
         #  - then pair name alphametically
         sorted_df = list_df.merge(performance, on='pair', how='left')\
-            .fillna(0).sort_values(by=['count', 'pair'], ascending=True)\
+            .fillna(0).sort_values(by=['count', 'prior_idx'], ascending=True)\
             .sort_values(by=['profit_ratio'], ascending=False)
         if self._min_profit is not None:
             removed = sorted_df[sorted_df['profit_ratio'] < self._min_profit]

tests/conftest_trades_usdt.py

@@ -342,7 +342,8 @@ def mock_trade_usdt_7(fee):
         stake_amount=20.0,
         amount=2.0,
         amount_requested=2.0,
-        open_date=datetime.now(tz=timezone.utc) - timedelta(minutes=5),
+        open_date=datetime.now(tz=timezone.utc) - timedelta(minutes=20),
+        close_date=datetime.now(tz=timezone.utc) - timedelta(minutes=5),
         fee_open=fee.return_value,
         fee_close=fee.return_value,
         is_open=False,

tests/plugins/test_pairlist.py

@@ -740,6 +740,33 @@ def test_PerformanceFilter_lookback(mocker, default_conf_usdt, fee, caplog) -> N
         assert pm.whitelist == ['ETH/USDT', 'XRP/USDT', 'NEO/USDT', 'TKN/USDT']
 
 
+@pytest.mark.usefixtures("init_persistence")
+def test_PerformanceFilter_keep_mid_order(mocker, default_conf_usdt, fee, caplog) -> None:
+    default_conf_usdt['exchange']['pair_whitelist'].extend(['ADA/USDT', 'ETC/USDT'])
+    default_conf_usdt['pairlists'] = [
+        {"method": "StaticPairList", "allow_inactive": True},
+        {"method": "PerformanceFilter", "minutes": 60, }
+    ]
+    mocker.patch('freqtrade.exchange.Exchange.exchange_has', return_value=True)
+    exchange = get_patched_exchange(mocker, default_conf_usdt)
+    pm = PairListManager(exchange, default_conf_usdt)
+    pm.refresh_pairlist()
+
+    assert pm.whitelist == ['ETH/USDT', 'LTC/USDT', 'XRP/USDT',
+                            'NEO/USDT', 'TKN/USDT', 'ADA/USDT', 'ETC/USDT']
+
+    with time_machine.travel("2021-09-01 05:00:00 +00:00") as t:
+        create_mock_trades_usdt(fee)
+        pm.refresh_pairlist()
+        assert pm.whitelist == ['XRP/USDT', 'ETC/USDT', 'ETH/USDT',
+                                'NEO/USDT', 'TKN/USDT', 'ADA/USDT', 'LTC/USDT']
+        # assert log_has_re(r'Removing pair .* since .* is below .*', caplog)
+
+        # Move to "outside" of lookback window, so original sorting is restored.
+        t.move_to("2021-09-01 07:00:00 +00:00")
+        pm.refresh_pairlist()
+        assert pm.whitelist == ['ETH/USDT', 'LTC/USDT', 'XRP/USDT',
+                                'NEO/USDT', 'TKN/USDT', 'ADA/USDT', 'ETC/USDT']
 
 
 def test_gen_pair_whitelist_not_supported(mocker, default_conf, tickers) -> None:
@@ -1170,13 +1197,13 @@ def test_pairlistmanager_no_pairlist(mocker, whitelist_conf):
       {'pair': 'TKN/BTC', 'profit_ratio': -0.0501, 'count': 2},
       {'pair': 'ETH/BTC', 'profit_ratio': -0.0501, 'count': 100}],
      ['TKN/BTC', 'ETH/BTC', 'LTC/BTC']),
-    # Tie in performance and count, broken by alphabetical sort
+    # Tie in performance and count, broken by prior sorting sort
     ([{"method": "StaticPairList"}, {"method": "PerformanceFilter"}],
      ['ETH/BTC', 'TKN/BTC', 'LTC/BTC'],
      [{'pair': 'LTC/BTC', 'profit_ratio': -0.0501, 'count': 1},
       {'pair': 'TKN/BTC', 'profit_ratio': -0.0501, 'count': 1},
       {'pair': 'ETH/BTC', 'profit_ratio': -0.0501, 'count': 1}],
-     ['ETH/BTC', 'LTC/BTC', 'TKN/BTC']),
+     ['ETH/BTC', 'TKN/BTC', 'LTC/BTC']),
 ])
 def test_performance_filter(mocker, whitelist_conf, pairlists, pair_allowlist, overall_performance,
                             allowlist_result, tickers, markets, ohlcv_history_list):