1 files changed, 78 insertions, 0 deletions
diff --git a/astro/region.py b/astro/region.py
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+++ b/astro/region.py
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+# -*- coding: utf-8 -*-
+#
+# Aaron Li
+# 2015/06/19
+
+"""
+Class Region for regions on the spherical surface.
+Used in astronomy to select/define a certian region, e.g, DS9.
+"""
+
+import sys
+
+
+class Region(object):
+    """
+    Basic region class for regions on the spherical surface,
+    similar definition as to DS9 regions.
+
+    Coordinate style: (ra, dec)
+    Unit: degree
+    ra: [0, 2\pi)
+    dec: [-\pi/2, \pi/2]
+    """
+
+    # currently supported region types (similar to DS9)
+    REGION_TYPES = ["circle", "ellipse", "box", "annulus", "pie", "panda"]
+
+    def __init__(self, regtype, xc, yc,
+            radius=None, radius2=None,
+            width=None, height=None, rotation=None,
+            start=None, end=None):
+        if regtype.lower() not in self.REGION_TYPES:
+            raise ValueError("only following region types supported: %s" %\
+                    " ".join(self.REGION_TYPES))
+        self.regtype = regtype.lower()
+        self.xc = xc
+        self.yc = yc
+        self.radius = radius
+        self.radius2 = radius2
+        self.width = width
+        self.height = height
+        self.rotation = rotation
+
+    def __repr__(self):
+        return "Region: %s" % self.regtype
+
+    def dump(self):
+        return {"regtype": self.regtype,
+                "xc": self.xc,
+                "yc": self.yc,
+                "radius": self.radius,
+                "radius2": self.radius2,
+                "width": self.width,
+                "height": self.height,
+                "rotation": self.rotation
+               }
+
+    def is_inside(self, point):
+        """
+        Determine whether the given point is inside the region.
+        """
+        x = point[0]
+        y = point[1]
+        if self.regtype == "box":
+            #print("WARNING: rotation box currently not supported!",
+            #        file=sys.stderr)
+            xmin = self.xc - self.width/2.0
+            xmax = self.xc + self.width/2.0
+            ymin = self.yc - self.height/2.0
+            ymax = self.yc + self.height/2.0
+            if all([x >= xmin, x <= xmax, y >= ymin, y <= ymax]):
+                return True
+            else:
+                return False
+        else:
+            raise ValueError("region type '%s' currently not implemented" %\
+                    self.regtype)
+