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Add function for setting default units from a std::map

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This is the form that will be used when reading units from a YAML
input file.
This commit is contained in:
Ray Speth 2018-12-18 14:17:14 -05:00
parent 4c5040e829
commit 6e3053dd1c
3 changed files with 72 additions and 0 deletions
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14
include/cantera/base/Units.h
View file

@ -111,6 +111,20 @@ public:
//! * To use CGS+mol: `setDefaults({"cm", "g", "mol"});`
void setDefaults(std::initializer_list<std::string> units);
//! Set the default units using a map of dimension to unit pairs.
//!
//! Defaults for dimensions not specified will be left unchanged. To use
//! Cantera's default units:
//! ```
//! UnitSystem system;
//! std::map<string, string> defaults{
//! {"length", "m"}, {"mass", "kg"}, {"time", "s"},
//! {"quantity", "kmol"}, {"pressure", "Pa"}, {"molar-energy", "J/kmol"}
//! };
//! setDefaults(defaults);
//! ```
void setDefaults(const std::map<std::string, std::string>& units);
//! Set the default units to convert from when using the `convertMolarEnergy`
//! function.
void setDefaultMolarEnergy(const std::string& e_units);

32
src/base/Units.cpp
View file

@ -68,6 +68,9 @@ const std::map<std::string, Units> knownUnits{
{"ohm", Units(1.0, 1, 2, -3, 0, -2)}, // kg*m^2/s^3/A^2
{"V", Units(1.0, 1, 2, -3, 0, -1)}, // kg*m^2/s^3/A
{"coulomb", Units(1.0, 0, 0, 1, 0, 1)}, // A*s
//! Molar energy units [M*L^2/T^2/Q]
{"J/kmol", Units(1.0, 1, 2, -2, 0, 0, -1)},
};
const std::map<std::string, double> prefixes{
@ -245,6 +248,35 @@ void UnitSystem::setDefaults(std::initializer_list<std::string> units)
}
}
void UnitSystem::setDefaults(const std::map<std::string, std::string>& units)
{
for (const auto& item : units) {
auto& name = item.first;
Units unit(item.second);
if (name == "mass" && unit.convertible(knownUnits.at("kg"))) {
m_mass_factor = unit.factor();
} else if (name == "length" && unit.convertible(knownUnits.at("m"))) {
m_length_factor = unit.factor();
} else if (name == "time" && unit.convertible(knownUnits.at("s"))) {
m_time_factor = unit.factor();
} else if (name == "temperature" && item.second == "K") {
// do nothing - no other temperature scales are supported
} else if (name == "current" && item.second == "A") {
// do nothing - no other current scales are supported
} else if (name == "quantity" && unit.convertible(knownUnits.at("kmol"))) {
m_quantity_factor = unit.factor();
} else if (name == "pressure" && unit.convertible(knownUnits.at("Pa"))) {
m_pressure_factor = unit.factor();
} else if (name == "molar-energy" && unit.convertible(knownUnits.at("J/kmol"))) {
m_molar_energy_factor = unit.factor();
} else {
throw CanteraError("UnitSystem::setDefaults",
"Unable to set default unit for '{}' to '{}' ({}).",
name, item.second, unit.str());
}
}
}
void UnitSystem::setDefaultMolarEnergy(const std::string& e_units)
{
Units u(e_units);

26
test/general/test_units.cpp
View file

@ -51,6 +51,32 @@ TEST(Units, with_defaults) {
EXPECT_DOUBLE_EQ(U.convert(1.0, "Pa*m^6/kmol"), 101325*1e-12*1000);
}
TEST(Units, with_defaults_map) {
std::map<std::string, std::string> defaults{
{"length", "cm"}, {"mass", "g"}, {"quantity", "mol"},
{"pressure", "atm"}
};
UnitSystem U;
U.setDefaults(defaults);
EXPECT_DOUBLE_EQ(U.convert(1.0, "m"), 0.01);
EXPECT_DOUBLE_EQ(U.convert(1.0, "kmol/m^3"), 1000);
EXPECT_DOUBLE_EQ(U.convert(1.0, "kg/kmol"), 1.0);
EXPECT_DOUBLE_EQ(U.convert(1.0, "cm^2"), 1.0);
EXPECT_DOUBLE_EQ(U.convert(1.0, "Pa"), 101325);
EXPECT_DOUBLE_EQ(U.convert(1.0, "hPa"), 1013.25);
EXPECT_DOUBLE_EQ(U.convert(1.0, "Pa*m^6/kmol"), 101325*1e-12*1000);
}
TEST(Units, bad_defaults) {
UnitSystem U;
std::map<std::string, std::string> bad_key{{"length", "m"}, {"joy", "MJ"}};
EXPECT_THROW(U.setDefaults(bad_key), CanteraError);
std::map<std::string, std::string> bad_value{{"length", "m"}, {"time", "J"}};
EXPECT_THROW(U.setDefaults(bad_value), CanteraError);
}
TEST(Units, activation_energies) {
UnitSystem U;
EXPECT_DOUBLE_EQ(U.convertMolarEnergy(1000, "J/kmol", "J/mol"), 1.0);