Add Python example for custom hierarchies

examples/14_custom_hierarchy.py

@@ -0,0 +1,45 @@
+import numpy as np
+import openpmd_api as io
+
+
+def main():
+    s = io.Series("../samples/custom_hierarchy.bp", io.Access.create)
+    it = s.write_iterations()[100]
+
+    # write openPMD part
+    temp = it.meshes["temperature"]
+    temp.axis_labels = ["x", "y"]
+    temp.unit_dimension = {io.Unit_Dimension.T: 1}
+    temp.position = [0.5, 0.5]
+    temp.grid_spacing = [1, 1]
+    temp.grid_global_offset = [0, 0]
+    temp.reset_dataset(io.Dataset(np.dtype("double"), [5, 5]))
+    temp[()] = np.zeros((5, 5))
+
+    # write NeXus part
+    nxentry = it["Scan:NXentry"]
+    nxentry.set_attribute("NX_class", "NXentry")
+    nxentry.set_attribute("default", "data")
+
+    data = nxentry["data:Nxdata"]
+    data.set_attribute("NX_class", "NXdata")
+    data.set_attribute("signal", "counts")
+    data.set_attribute("axes", ["two_theta"])
+    data.set_attribute("two_theta_indices", [0])
+
+    counts = data.datasets()["counts"]
+    counts.set_attribute("units", "counts")
+    counts.set_attribute("long_name", "photodiode counts")
+    counts.reset_dataset(io.Dataset(np.dtype("int"), [15]))
+    counts[()] = np.zeros(15, dtype=np.dtype("int"))
+
+    two_theta = data.datasets()["two_theta"]
+    two_theta.set_attribute("units", "degrees")
+    two_theta.set_attribute("long_name", "two_theta (degrees)")
+    two_theta.reset_dataset(io.Dataset(np.dtype("double"), [15]))
+    two_theta[()] = np.zeros(15)
+
+
+
+if __name__ == "__main__":
+    main()