From 61ceb7f224c4c93e93721c3b5b0e81f94387ef64 Mon Sep 17 00:00:00 2001
From: Dan Howe <d.howe@wrl.unsw.edu.au>
Date: Mon, 10 Sep 2018 19:06:02 +1000
Subject: [PATCH] Add dimensions() function

---
 scaling/froude.py    | 24 ++++++++++++++++++++++++
 tests/froude_test.py |  3 +++
 2 files changed, 27 insertions(+)

diff --git a/scaling/froude.py b/scaling/froude.py
index 9b2fc68..ba017b2 100644
--- a/scaling/froude.py
+++ b/scaling/froude.py
@@ -71,3 +71,27 @@ def model_to_proto(x_model, length_scale, from_unit, to_unit):
     length_scale_factor = length_scale
 
     return _convert(x_model, length_scale_factor, from_unit, to_unit)
+
+
+def dimensions(unit):
+    """Get unit dimensions.
+
+    Args:
+        unit (str):  unit name or symbol
+
+    Returns:
+        string containing unit dimensions
+    """
+
+    # Get dimensions of unit
+    dims = UREG(unit).dimensionality
+
+    dim_data = {'L': '[length]', 'M': '[mass]', 'T': '[time]'}
+
+    s = ''
+    for symbol, key in dim_data.items():
+        exponent = dims[key]
+        if exponent != 0:
+            s += '{}^{:g} '.format(symbol, exponent)
+
+    return s.strip()
diff --git a/tests/froude_test.py b/tests/froude_test.py
index 5b36462..82d7344 100644
--- a/tests/froude_test.py
+++ b/tests/froude_test.py
@@ -9,3 +9,6 @@ def test_froude_length():
 
 def test_froude_force():
     assert froude.model_to_proto(1, 10, 'N', 'N') == 1000
+
+def test_unit_dimensions():
+    assert froude.dimensions('N') == 'L^1 M^1 T^-2'