Add predator-prey data

tests/test_data.py

@@ -53,6 +53,7 @@ def _import_and_execute(name, kw_args, monkeypatch):
         ("mauna_loa", {"detrend_method": "gp"}),
         ("mauna_loa", {"detrend_method": "linear"}),
         ("miso", {}),
+        ("predprey", {}),
         ("toy_sines", {}),
         ("vix", {}),
     ],

wbml/data/predprey.py

@@ -0,0 +1,36 @@
+import pandas as pd
+
+from .data import data_path, resource
+
+__all__ = ["load"]
+
+
+def load():
+    """Predator–prey data.
+
+    Source:
+        The data is a digitised version of the historical data by D. R. Hundley:
+            http://people.whitman.edu/~hundledr/courses/M250F03/LynxHare.txt
+
+    Returns:
+        :class:`pd.DataFrame`: Predator–prey data.
+    """
+    _fetch()
+
+    df = pd.read_csv(
+        data_path("pred_prey", "LynxHare.txt"),
+        header=None,
+        delim_whitespace=True,
+        index_col=0,
+    )
+    df.index.name = "year"
+    df.columns = ["hare", "lynx"]
+
+    return df
+
+
+def _fetch():
+    resource(
+        target=data_path("pred_prey", "LynxHare.txt"),
+        url="http://people.whitman.edu/~hundledr/courses/M250F03/LynxHare.txt",
+    )