get all observations listed in artsdatabanken. Input is lat, lon and raidus of circle of which to include observations

get_obs_from_artsdatabank.py

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+import requests
+import pandas as pd
+import numpy as np
+from pyproj import Transformer
+
+# create transformer once (faster if used repeatedly)
+_transformer = Transformer.from_crs("EPSG:4326", "EPSG:3857", always_xy=True)
+
+
+def main(lat, lon, radius_m,
+                              n_vertices=15,
+                              page_size=10000,
+                              species_summary=False):
+    """
+    Fetch Artsdatabanken observations inside a semicircular polygon.
+
+    Parameters
+    ----------
+    lat : float
+    lon : float
+    radius_m : float
+        Radius in meters
+    n_vertices : int
+        Polygon vertices approximating the circle
+    page_size : int
+    species_summary : bool
+        If True, also return species counts
+
+    Returns
+    -------
+    pandas.DataFrame
+    (optional) pandas.Series with species counts
+    """
+
+    # -------------------
+    # Build polygon
+    # -------------------
+
+    cx, cy = _transformer.transform(lon, lat)
+
+    angles = np.linspace(0, 2*np.pi, n_vertices, endpoint=False)
+
+    x = np.float32(cx + radius_m * np.cos(angles))
+    y = np.float32(cy + radius_m * np.sin(angles))
+
+    points = [f"{xi}+{yi}" for xi, yi in zip(x, y)]
+    points.append(points[0])  # close polygon
+
+    polygon = "POLYGON((" + ",".join(points) + "))"
+
+    # -------------------
+    # API request
+    # -------------------
+
+    url = (
+        "https://artskart.artsdatabanken.no/publicapi/api/observations/list/"
+        f"?gmWktPolygon={polygon}&page=0&pageSize={page_size}"
+    )
+
+    r = requests.get(url)
+    r.raise_for_status()
+
+    data = r.json()
+
+    if "Observations" not in data:
+        return pd.DataFrame()
+
+    # -------------------
+    # Dataframe creation
+    # -------------------
+
+    df = pd.json_normalize(data["Observations"])[
+        ["Latitude", "Longitude", "Notes", "ScientificName", "ScientificNameId"]
+    ]
+
+    df["Latitude"] = df["Latitude"].str.replace(",", ".").astype(float)
+    df["Longitude"] = df["Longitude"].str.replace(",", ".").astype(float)
+
+    if species_summary:
+        return df, df["ScientificName"].value_counts()
+
+    return df