Add calculate_available_volume function

betfairutil/__init__.py

@@ -1540,6 +1540,37 @@ def calculate_book_percentage(
     return sum(implied_probabilities)
 
 
+def calculate_available_volume(
+    market_book: Union[Dict[str, Any], MarketBook],
+    side: Side,
+    max_book_percentage: float,
+) -> float:
+    """
+    Calculate the available volume up to a maximum book_percentage value.
+
+    :param market_book: A market book either as a dictionary or betfairlightweight MarketBook object
+    :param side: Indicate whether to get the available volume on the back or lay side.
+    :param max_book_percentage: Maximum book_percentage value to use for calculating the volume.
+    :return: Available total volume.
+    """
+    available_volume = 0
+    for depth in itertools.count():
+        book_percentage = 0
+        size = 0
+        for runner in market_book["runners"]:
+            runner_price_size = get_price_size_by_depth(
+                runner=runner, side=side, depth=depth
+            )
+            if runner_price_size:
+                book_percentage += 1.0 / runner_price_size["price"]
+                size += runner_price_size["size"]
+            else:
+                return available_volume
+
+        if book_percentage <= max_book_percentage:
+            available_volume += size
+
+
 def calculate_market_book_diff(
     current_market_book: Union[Dict[str, Any], MarketBook],
     previous_market_book: Union[Dict[str, Any], MarketBook],

tests/test_non_prices.py

@@ -13,6 +13,7 @@
 from betfairlightweight.resources import RunnerBook
 from pyrsistent import pmap
 
+from betfairutil import calculate_available_volume
 from betfairutil import calculate_book_percentage
 from betfairutil import calculate_market_book_diff
 from betfairutil import calculate_order_book_imbalance
@@ -1119,3 +1120,16 @@ def test_get_first_market_definition_from_prices_file(
 
 def test_get_winners_from_prices_file(path_to_prices_file: Path):
     assert get_winners_from_prices_file(path_to_prices_file) == []
+
+
+def test_calculate_available_volume(market_book: Dict[str, Any]):
+    assert calculate_available_volume(market_book, Side.BACK, 1.05) == 2
+
+    market_book["runners"][0]["ex"]["availableToBack"].append(
+        {"price": 1.96, "size": 1}
+    )
+    market_book["runners"][1]["ex"]["availableToBack"].append(
+        {"price": 1.96, "size": 1}
+    )
+    assert calculate_available_volume(market_book, Side.BACK, 1.05) == 4
+    assert calculate_available_volume(market_book, Side.BACK, 1.02) == 2