Added generate_update_pair function to python

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>

Web/coolprop/HighLevelAPI.rst

@@ -46,16 +46,16 @@ The phase index (as floating point number) can also be obtained using the PropsS
     
     In [5]: CoolProp.CoolProp.PropsSI('Phase','P',101325,'Q',0,'Water')
     
-where you can obtain the integer indices corresponding to the phase flags using the ``get_parameter_index`` function:
+where you can obtain the integer indices corresponding to the phase flags using the ``get_phase_index`` function:
 
 .. ipython::
 
     In [1]: import CoolProp
 
-    In [6]: CoolProp.CoolProp.get_parameter_index('phase_twophase')
+    In [6]: CoolProp.CoolProp.get_phase_index('phase_twophase')
     
     # Or for liquid
-    In [6]: CoolProp.CoolProp.get_parameter_index('phase_liquid')
+    In [6]: CoolProp.CoolProp.get_phase_index('phase_liquid')
     
 For a given fluid, the phase can be plotted in T-p coordinates:
 

include/DataStructures.h

@@ -131,13 +131,27 @@ enum parameters{
 };
 // !! If you add a parameter, update the map in the corresponding CPP file !!
 
+/// These are constants for the phases of the fluid
+enum phases{iphase_liquid, ///< Subcritical liquid 
+            iphase_supercritical, ///< Supercritical (p > pc, T > Tc)
+            iphase_supercritical_gas, ///< Supercritical gas (p < pc, T > Tc)
+            iphase_supercritical_liquid, ///< Supercritical liquid (p > pc, T < Tc)
+            iphase_critical_point, ///< At the critical point
+            iphase_gas, ///< Subcritical gas
+            iphase_twophase, ///< Twophase
+            iphase_unknown, ///< Unknown phase
+            iphase_not_imposed}; ///< Phase is not imposed
+
 /// Return information about the parameter
 /// @param key The key, one of iT, iP, etc.
 /// @param info The thing you want, one of "IO" ("IO" if input/output, "O" if output only), "short" (very short description), "long" (a longer description), "units"
 std::string get_parameter_information(int key, std::string info);
 
-/// Return the integer key corresponding to the parameter name ("Dmolar" for instance)
-int get_parameter_index(const std::string &param_name);
+/// Return the enum key corresponding to the parameter name ("Dmolar" for instance)
+parameters get_parameter_index(const std::string &param_name);
+
+/// Return the enum key corresponding to the phase name ("phase_liquid" for instance)
+phases get_phase_index(const std::string &param_name);
 
 /// Returns true if the input is trivial (constants, critical parameters, etc.)
 bool is_trivial_parameter(int key);
@@ -156,17 +170,6 @@ enum composition_types{IFRAC_MASS, IFRAC_MOLE, IFRAC_VOLUME, IFRAC_UNDEFINED, IF
 
 const long double R_u_CODATA = 8.3144621; ///< The value for the ideal gas constant in J/mol/K according to CODATA 2010.  This value is used to harmonize all the ideal gas constants.  This is especially important in the critical region.
 
-/// These are constants for the phases of the fluid
-enum phases{iphase_liquid, ///< Subcritical liquid 
-            iphase_supercritical, ///< Supercritical (p > pc, T > Tc)
-            iphase_supercritical_gas, ///< Supercritical gas (p < pc, T > Tc)
-            iphase_supercritical_liquid, ///< Supercritical liquid (p > pc, T < Tc)
-            iphase_critical_point, ///< At the critical point
-            iphase_gas, ///< Subcritical gas
-            iphase_twophase, ///< Twophase
-            iphase_unknown, ///< Unknown phase
-            iphase_not_imposed}; ///< Phase is not imposed
-
 /// These are unit types for the fluid
 enum fluid_types{FLUID_TYPE_PURE, FLUID_TYPE_PSEUDOPURE, FLUID_TYPE_REFPROP, FLUID_TYPE_INCOMPRESSIBLE_LIQUID, FLUID_TYPE_INCOMPRESSIBLE_SOLUTION, FLUID_TYPE_UNDEFINED};
 
@@ -214,12 +217,12 @@ enum input_pairs{
 };
 // !! If you add or remove a parameter, update the map in the corresponding CPP file !!
 
-inline bool match_pair(long key1, long key2, long x1, long x2, bool &swap)
+inline bool match_pair(parameters key1, parameters key2, parameters x1, parameters x2, bool &swap)
 {
     swap = !(key1 == x1);
     return ((key1 == x1 && key2 == x2) || (key2 == x1 && key1 == x2));
 };
-template<class T> CoolProp::input_pairs generate_update_pair(long key1, T value1, long key2, T value2, T &out1, T&out2)
+template<class T> CoolProp::input_pairs generate_update_pair(parameters key1, T value1, parameters key2, T value2, T &out1, T &out2)
     {
         CoolProp::input_pairs pair;
         bool swap;

src/CoolProp.cpp

@@ -384,8 +384,8 @@ double _PropsSI(const std::string &Output, const std::string &Name1, double Prop
         return val;
     }
     
-    long iName1 = get_parameter_index(Name1);
-    long iName2 = get_parameter_index(Name2);
+    parameters iName1 = get_parameter_index(Name1);
+    parameters iName2 = get_parameter_index(Name2);
 
     if (State->using_mole_fractions()){
         State->set_mole_fractions(fractions);

src/Tests/CoolProp-Tests.cpp

@@ -256,8 +256,8 @@ public:
     }
     void set_pair(std::string &in1, double v1, std::string &in2, double v2){
         double o1, o2;
-        long iin1 = CoolProp::get_parameter_index(in1);
-        long iin2 = CoolProp::get_parameter_index(in2);
+        parameters iin1 = CoolProp::get_parameter_index(in1);
+        parameters iin2 = CoolProp::get_parameter_index(in2);
         CoolProp::input_pairs pair = CoolProp::generate_update_pair(iin1, v1, iin2, v2, o1, o2);
         pState->update(pair, o1, o2);
     }

wrappers/Python/CoolProp/CoolProp.pxd

@@ -25,7 +25,8 @@ cdef extern from "Configuration.h" namespace "CoolProp":
 cdef extern from "DataStructures.h" namespace "CoolProp":    
     string _get_parameter_information "CoolProp::get_parameter_information"(int, string) except +
     int _get_parameter_index "CoolProp::get_parameter_index"(string) except +
-    constants_header.input_pairs _generate_update_pair "CoolProp::generate_update_pair"(long key1, double value1, long key2, double value2, double &out1, double &out2) except +
+    int _get_phase_index "CoolProp::get_phase_index"(string) except +
+    constants_header.input_pairs _generate_update_pair "CoolProp::generate_update_pair"(constants_header.parameters key1, double value1, constants_header.parameters key2, double value2, double &out1, double &out2) except +
     
 cdef extern from "CoolPropLib.h":
     double _Props "Props"(const char* Output, const char Name1, double Prop1, const char Name2, double Prop2, const char* Ref)

wrappers/Python/CoolProp/CoolProp.pyx

@@ -117,14 +117,36 @@ def set_reference_state(string FluidName, *args):
 #     else:
 #         return val
 
+cpdef tuple generate_update_pair(constants_header.parameters key1, double value1, constants_header.parameters key2, double value2):
+    """
+    This function will generate an input pair to the update() function given the key, value pairs for both inputs
+    """
+    cdef constants_header.input_pairs pair
+    cdef double out1, out2
+    pair = _generate_update_pair(key1, value1, key2, value2, out1, out2)
+    return pair, out1, out2
+
 cpdef string get_config_as_json_string():
+    """
+    Obtain a json formulation of the internal configuration in CoolProp
+    
+    Values can be set by passing a modified json library (converted to string) to set_config_as_json_string
+    """
     return _get_config_as_json_string()
 
 cpdef set_config_as_json_string(string s):
+    """
+    Set the internal configuration in CoolProp from a json data string
+    
+    Current state can be obtained by calling get_config_as_json_string
+    """
     _set_config_as_json_string(s)
     
 cpdef int get_parameter_index(string key):
     return _get_parameter_index(key)
+    
+cpdef int get_phase_index(string key):
+    return _get_phase_index(key)
 
 cpdef string get_parameter_information(int key, string info):
     return _get_parameter_information(key, info)