Gunnstein#22 avoiding unsteady effects when checking a slice of a loa…

…d data set as described in Gunnstein#22.

- Including test case
- bugfix in get_load_class_boundaries() unsing k+1 instead of k+2

fatpack/rainflow.py

@@ -38,15 +38,18 @@ def get_load_classes(y, k=64):
     return np.linspace(ymin, ymax, k+1)
 
 
-def get_load_class_boundaries(y, k=64):
-    ymin, ymax = y.min(), y.max()
+def get_load_class_boundaries(y, k=64, ymin=None, ymax=None):
+    if ymin is None:
+        ymin = y.min()
+    if ymax is None:
+        ymax = y.max()
     dy = (ymax-ymin) / (2.0*k)
     y0 = ymin - dy
     y1 = ymax + dy
-    return np.linspace(y0, y1, k+2)
+    return np.linspace(y0, y1, k+1)
 
 
-def find_reversals_strict(y, k=64):
+def find_reversals_strict(y, k=64, ymin=None, ymax=None):
     """Return reversals (peaks and valleys) and indices of reversals in `y`.
 
     The data points in the dataseries `y` are classified into `k` constant
@@ -64,6 +67,10 @@ class boundary are rounded upwards if the reversal is a peak and downwards
     k : int
         The number of intervals to divide the min-max range of the dataseries
         into.
+    ymin : float
+        min value of data series
+    ymin : float
+        max value of data series
 
     Returns
     -------
@@ -81,7 +88,7 @@ class boundary are rounded upwards if the reversal is a peak and downwards
 
     y = y.copy()  # Make sure we do not change the original sequence
     sgn = np.sign
-    Y = get_load_class_boundaries(y, k)
+    Y = get_load_class_boundaries(y, k, ymin, ymax)
     dY = Y[1] - Y[0]
 
     # Classifying points into levels
@@ -128,7 +135,7 @@ class boundary are rounded upwards if the reversal is a peak and downwards
     return y[revix], np.array(revix)
 
 
-def find_reversals(y, k=64):
+def find_reversals(y, k=64, ymin=None, ymax=None):
     """Return reversals (peaks and valleys) and indices of reversals in `y`.
 
     The data points in the dataseries `y` are classified into `k` constant
@@ -142,6 +149,10 @@ def find_reversals(y, k=64):
     k : int
         The number of intervals to divide the min-max range of the dataseries
         into.
+    ymin : float
+        min value of data series
+    ymin : float
+        max value of data series
 
     Returns
     -------
@@ -167,7 +178,7 @@ def find_reversals(y, k=64):
 
     """
 
-    Y = get_load_class_boundaries(y, k)
+    Y = get_load_class_boundaries(y, k, ymin=ymin, ymax=ymax)
     dY = Y[1] - Y[0]
 
     # Classifying points into levels

fatpack/test.py

@@ -52,6 +52,8 @@
             class_boundaries = np.array([
                                 0.5,  1.5,  2.5,  3.5, 4.5, 5.5, 6.5, 7.5, 8.5,
                                 9.5, 10.5, 11.5, 12.5]),
+            class_boundaries_minmax = np.array([-5.5, -3.5, -1.5,  0.5,  2.5,  4.5,  6.5,  8.5, 10.5, 12.5,
+                                                  14.5, 16.5, 18.5]),
             starting_destination_rainflow_matrix = np.array(
                             [[ 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 1.],
                              [ 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
@@ -81,7 +83,7 @@ class TestFindReversalsStrict(BaseArrayTestCase, unittest.TestCase):
     def setUp(self):
         self.result_true = TESTDATA['reversals']
         y = TESTDATA['dataseries']
-        self.result, __ = find_reversals_strict(y, k=11)
+        self.result, __ = find_reversals_strict(y, k=12)
 
 
 class TestConcatenateResidue(BaseArrayTestCase, unittest.TestCase):
@@ -123,14 +125,22 @@ class TestGetLoadClasses(BaseArrayTestCase, unittest.TestCase):
     def setUp(self):
         self.result_true = TESTDATA['classes']
         y = TESTDATA['dataseries']
-        self.result = get_load_classes(y, k=11)
+        self.result = get_load_classes(y, k=12)
 
 
 class TestGetLoadClassBoundaries(BaseArrayTestCase, unittest.TestCase):
     def setUp(self):
         self.result_true = TESTDATA['class_boundaries']
         y = TESTDATA['dataseries']
-        self.result = get_load_class_boundaries(y, k=11)
+        self.result = get_load_class_boundaries(y, k=12)
+
+
+class TestGetLoadClassBoundariesMinMax(BaseArrayTestCase, unittest.TestCase):
+    def setUp(self):
+        self.result_true = TESTDATA['class_boundaries_minmax']
+        y = TESTDATA['dataseries']
+        yRange = np.max(y) - np.min(y)
+        self.result = get_load_class_boundaries(y, k=12, ymin=np.min(y) - yRange/2, ymax=np.max(y) + yRange/2)
 
 
 class TestFindRainflowMatrix(BaseArrayTestCase, unittest.TestCase):
@@ -161,7 +171,7 @@ class TestFindRainflowRangesStrict(BaseArrayTestCase, unittest.TestCase):
     def setUp(self):
         self.result_true = TESTDATA['ranges_total_strict']
         self.result = find_rainflow_ranges_strict(
-                                                TESTDATA['dataseries'], k=11)
+                                                TESTDATA['dataseries'], k=12)
 
 
 class TestFindRangeCount(unittest.TestCase):