Added error checking to public interface of the package

2 files changed, 15 insertions, 2 deletions

diff --git a/szilagyi/__init__.py b/szilagyi/__init__.py
index 99ba9fc..ce6e840 100644
--- a/szilagyi/__init__.py
+++ b/szilagyi/__init__.py
@@ -1 +1,14 @@
-from .nomogram import calculate_swi
+from .nomogram import calculate_swi as _calculate_swi
+
+
+def calculate_swi(temperature_difference, convective_cloud_depth):
+	"""
+	Calculates the Szilagyi Waterspout Index for *temperature_difference* and *convective_cloud_depth*.
+
+	May raise :exc:`ValueError` if the values are not in range of the original nomogram.
+	"""
+	if temperature_difference < 0 or temperature_difference > 40:
+		raise ValueError("temperature_difference must be within <0, 40> range")
+	if convective_cloud_depth < 0 or convective_cloud_depth > 50000:
+		raise ValueError("convective_cloud_depth must be within <0, 50000> range")
+	return _calculate_swi(temperature_difference, convective_cloud_depth)
diff --git a/szilagyi/plots.py b/szilagyi/plots.py
index 516efd1..31b8af2 100644
--- a/szilagyi/plots.py
+++ b/szilagyi/plots.py
@@ -3,7 +3,7 @@ import math
 import matplotlib.pyplot as plot
 
 from . import _dataset
-from . import calculate_swi
+from .nomogram import calculate_swi
 
 
 MAX_X = 40