Add Python interface for setState_RP + tests

interfaces/cython/cantera/_cantera.pxd

@@ -176,6 +176,7 @@ cdef extern from "cantera/thermo/ThermoPhase.h" namespace "Cantera":
         void setState_UV(double, double) except +
         void setState_SP(double, double) except +
         void setState_SV(double, double) except +
+        void setState_RP(double, double) except +
 
         # molar thermodynamic properties:
         double enthalpy_mole() except +

interfaces/cython/cantera/test/test_thermo.py

@@ -295,6 +295,13 @@ class TestThermoPhase(utilities.CanteraTest):
         self.phase.SVY = s1, v1, Y1
         check_state(T1, rho1, Y1)
 
+        self.phase.TDY = T0, rho0, Y0
+        self.phase.DPX = rho1, P1, X1
+        check_state(T1, rho1, Y1)
+
+        self.phase.TDY = T0, rho0, Y0
+        self.phase.DPY = rho1, P1, Y1
+        check_state(T1, rho1, Y1)
 
     def test_setState_mass(self):
         self.check_setters(T1 = 500.0, rho1 = 1.5,
@@ -379,6 +386,20 @@ class TestThermoPhase(utilities.CanteraTest):
         self.assertNear(V, self.phase.v)
         self.assertArrayNear(X, self.phase.X)
 
+        D,P,X = self.phase.DPX
+        self.assertNear(D, self.phase.density)
+        self.assertNear(P, self.phase.P)
+        self.assertArrayNear(X, self.phase.X)
+
+        D,P,Y = self.phase.DPY
+        self.assertNear(D, self.phase.density)
+        self.assertNear(P, self.phase.P)
+        self.assertArrayNear(Y, self.phase.Y)
+
+        D,P = self.phase.DP
+        self.assertNear(D, self.phase.density)
+        self.assertNear(P, self.phase.P)
+
     def test_getState_mass(self):
         self.phase.TDY = 350.0, 0.7, 'H2:0.1, H2O2:0.1, AR:0.8'
         self.check_getters()

interfaces/cython/cantera/thermo.pyx

@@ -886,6 +886,35 @@ cdef class ThermoPhase(_SolutionBase):
             self.thermo.setState_UV(U / self._mass_factor(),
                                     V / self._mass_factor())
 
+    property DP:
+        def __get__(self):
+            return self.density, self.P
+        def __set__(self, values):
+            assert len(values) == 2
+            D = values[0] if values[0] is not None else self.density
+            P = values[1] if values[1] is not None else self.P
+            self.thermo.setState_RP(D*self._mass_factor(), P)
+
+    property DPX:
+        def __get__(self):
+            return self.density, self.P, self.X
+        def __set__(self, values):
+            assert len(values) == 3
+            D = values[0] if values[0] is not None else self.density
+            P = values[1] if values[1] is not None else self.P
+            self.X = values[2]
+            self.thermo.setState_RP(D*self._mass_factor(), P)
+
+    property DPY:
+        def __get__(self):
+            return self.density, self.P, self.Y
+        def __set__(self, values):
+            assert len(values) == 3
+            D = values[0] if values[0] is not None else self.density
+            P = values[1] if values[1] is not None else self.P
+            self.Y = values[2]
+            self.thermo.setState_RP(D*self._mass_factor(), P)
+
     property HP:
         """Get/Set enthalpy [J/kg or J/kmol] and pressure [Pa]."""
         def __get__(self):