Merge pull request #5 from mpewsey/v1.1.0

Add polygon

docs/releases/v1.1.0.rst

@@ -3,3 +3,4 @@ Release Notes v1.1.0
 ====================
 
 * Updated package for compatibility with Python 2.7.
+* Added polygon functions.

examples/polygon_ex1.py

@@ -0,0 +1,5 @@
+# polygon_ex1.py
+from xsect import polygon_points, plot_section
+
+points = polygon_points(5, 1, 0.1)
+plot_section(points, title='Polygon')

xsect/calc/__init__.py

@@ -88,6 +88,20 @@
  round_summary
 
 
+Polygon Functions
+=================
+The following functions may be used to calculate the cross sectional properties
+for solid or thin walled polygon sections.
+
+.. plot:: ../examples/polygon_ex1.py
+
+.. autosummary::
+ :toctree: generated/
+
+ polygon_points
+ polygon_summary
+
+
 Angle Functions
 ===============
 The following functions may be used to calculate cross sectional properties
@@ -165,5 +179,6 @@
 from .double_angle import *
 from .i_beam import *
 from .multi import *
+from .polygon import *
 from .round import *
 from .t_beam import *

xsect/calc/_plt.py

@@ -0,0 +1,11 @@
+# This module configures matplotlib
+
+import os
+import matplotlib
+
+if 'DISPLAY' not in os.environ:
+ matplotlib.use('Agg')
+
+import matplotlib.pyplot as plt
+
+__all__ = ['plt']

xsect/calc/boundary.py

@@ -1,10 +1,6 @@
 from __future__ import division
-import os
 import numpy as np
-import matplotlib
-if os.environ.get('DISPLAY', None) is None:
- matplotlib.use('Agg')
-import matplotlib.pyplot as plt
+from ._plt import plt
 
 __all__ = [
  'rotate2',

xsect/calc/boundary_test.py

@@ -53,9 +53,6 @@ def test_area():
  points = sample_angles(rand)
  sol = np.array([area(x) for x in points])
 
- print(sol)
- print(a)
-
  assert approx(sol, 0.01) == a
 
 

xsect/calc/cross_section.py

@@ -97,8 +97,8 @@ def __repr__(self):
  s = ['{}={!r}'.format(k, getattr(self, k)) for k in attrs]
  return '{}({})'.format(type(self).__name__, ', '.join(s))
 
- @staticmethod
- def from_points(name, add, subtract=[], is_round=False,
+ @classmethod
+ def from_points(cls, name, add, subtract=[], is_round=False,
  include_meta=True, **kwargs):
  """
  Initializes a cross section from boundary points.
@@ -132,16 +132,16 @@ def from_points(name, add, subtract=[], is_round=False,
  odict['is_round'] = is_round
  odict.update(kwargs)
 
- xsect = CrossSection(**odict)
+ xsect = cls(**odict)
 
  if not include_meta:
  xsect.meta.clear()
 
  return xsect
 
 
- @staticmethod
- def from_aisc(name, metric=False, version=None, include_meta=True):
+ @classmethod
+ def from_aisc(cls, name, metric=False, version=None, include_meta=True):
  """
  Initializes a cross section from the properties in the AISC database.
 
@@ -172,7 +172,7 @@ def from_aisc(name, metric=False, version=None, include_meta=True):
  if odict['type'] == 'PIPE':
  odict['is_round'] = True
 
- xsect = CrossSection(**odict)
+ xsect = cls(**odict)
 
  if not include_meta:
  xsect.meta.clear()

xsect/calc/multi.py

@@ -1,10 +1,6 @@
 from __future__ import division
-import os
 import numpy as np
-import matplotlib
-if os.environ.get('DISPLAY', None) is None:
- matplotlib.use('Agg')
-import matplotlib.pyplot as plt
+from ._plt import plt
 from .boundary import TOL, area, centroid, inertias, close_points, rotate2
 
 __all__ = [

xsect/calc/polygon.py

@@ -0,0 +1,66 @@
+from __future__ import division
+import numpy as np
+from .boundary import close_points, section_summary
+
+__all__ = ['polygon_points', 'polygon_summary']
+
+
+def polygon_points(n, radius, thickness=None, is_inscribed=True):
+ """
+ Returns an array of boundary points for a polygon.
+
+ Parameters
+ ----------
+ n : int
+ The number of sides to the polygon.
+ radius : float
+ The radius of the polygon.
+ thickness : float
+ The thickness of the wall. If None, the cross section will be assumed
+ to be solid.
+ is_inscribed : bool
+ If True, an inscribed polygon will be generated for the specified
+ radius. Otherwise, a circumscribed polygon will be generated.
+ """
+ c = np.cos(np.pi/n)
+
+ if is_inscribed:
+ ro = radius
+ else:
+ ro = radius / c
+
+ ang = np.linspace(0.5*np.pi, 2.5*np.pi, n+1)
+ ang = np.column_stack([np.cos(ang), np.sin(ang)])
+ points = ro * ang
+
+ if thickness is not None:
+ if is_inscribed:
+ ri = ro - thickness / c
+ else:
+ ri = (radius - thickness) / c
+
+ p = ri * ang[::-1]
+ points = np.concatenate([points, p])
+
+ return close_points(points)
+
+
+def polygon_summary(n, radius, thickness=None, is_inscribed=True):
+ """
+ Returns a dictionary with a summary of polygon section properties.
+
+ Parameters
+ ----------
+ n : int
+ The number of sides to the polygon.
+ radius : float
+ The radius of the polygon.
+ thickness : float
+ The thickness of the wall. If None, the cross section will be assumed
+ to be solid.
+ is_inscribed : bool
+ If True, an inscribed polygon will be generated for the specified
+ radius. Otherwise, a circumscribed polygon will be generated.
+ """
+ p = polygon_points(n, radius, thickness, is_inscribed)
+ return section_summary(p)

xsect/calc/polygon_test.py

@@ -0,0 +1,21 @@
+import pytest
+import numpy as np
+from .polygon import *
+
+
+def test_polygon_summary():
+ # Inscribed
+ p = polygon_summary(6, 1, is_inscribed=True)
+ assert pytest.approx(p['area']) == 2.5980762113533
+
+ p = polygon_summary(6, 1, 0.1, is_inscribed=True)
+ a = 2.5980762113533 - 2.0327172275047
+ assert pytest.approx(p['area']) == a
+
+ # Circumscribed
+ p = polygon_summary(6, 1, is_inscribed=False)
+ assert pytest.approx(p['area']) == 3.4641016151378
+
+ p = polygon_summary(6, 1, 0.1, is_inscribed=False)
+ a = 3.4641016151378 - 2.8059223082616
+ assert pytest.approx(p['area']) == a