pije76 · June 17, 2025 07:15 · Jan 20, 2018
diff --git a/mercator_numpy.py b/mercator_numpy.py
@@ -0,0 +1,37 @@
+
+"""
+projects a numpy array with (lon, lat) to (x, y) in mercator coordinates using numpy
+license: MIT
+adapted from https://github.com/mapbox/mercantile
+"""
+
+import numpy as np
+import math
+
+def xy(lnglat, truncate=False):
+    """Convert longitude and latitude to web mercator x, y
+    Parameters
+    ----------
+    lnglat : np.array
+        Longitude and latitude array in decimal degrees, shape: (-1, 2)
+    truncate : bool, optional
+        Whether to truncate or clip inputs to web mercator limits.
+    Returns
+    -------
+    np.array with x, y in webmercator
+
+    >>> a = np.array([(0.0, 0.0), (-75.15963, -14.704620000000013)])
+    >>> b = np.array(((0.0, 0.0), (-8366731.739810849, -1655181.9927159143)))
+    >>> np.isclose(xy(a), b)
+    array([[ True,  True],
+           [ True,  True]], dtype=bool)
+    """
+
+    lng, lat = lnglat[:,0], lnglat[:, 1]
+    if truncate:
+        lng = numpy.clip(lng, -180.0, 180.0)
+        lat = numpy.clip(lng, -90.0, 90.0)
+    x = 6378137.0 * np.radians(lng)
+    y = 6378137.0 * np.log(
+        np.tan((math.pi * 0.25) + (0.5 * np.radians(lat))))
+    return np.array((x, y)).T