first draft

Author: narmstro2020

wpiunits/generate_units.py

@@ -77,7 +77,7 @@ def output(output_dir, outfn: str, contents: str):
     },
     "AngularVelocity": {
         "base_unit": "RadiansPerSecond",
-        "multiply": {"Time": "Angle", "Frequency": "AngularAcceleration"},
+        "multiply": {"Time": "Angle", "Frequency": "AngularAcceleration", "Torque" : "Power"},
         "divide": {"Time": "AngularAcceleration"},
         "extra": inspect.cleandoc(
             """
@@ -222,7 +222,7 @@ def output(output_dir, outfn: str, contents: str):
         "multiply": {
             "Time": "Energy",
         },
-        "divide": {"Voltage": "Current", "Current": "Voltage", "Energy": "Frequency"},
+        "divide": {"Voltage": "Current", "Current": "Voltage", "Energy": "Frequency", "Torque" : "AngularVelocity", "AngularVelocity" : "Torque"},
     },
     "Resistance": {
         "base_unit": "Ohms",
@@ -258,7 +258,7 @@ def output(output_dir, outfn: str, contents: str):
     },
     "Torque": {
         "base_unit": "NewtonMeters",
-        "multiply": {},
+        "multiply": {"AngularVelocity : Power"},
         "divide": {"Distance": "Force", "Force": "Distance"},
     },
     "Velocity": {

wpiunits/src/main/java/edu/wpi/first/units/AngularVelocityUnit.java

@@ -4,6 +4,8 @@
 
 package edu.wpi.first.units;
 
+import static edu.wpi.first.units.Units.Watts;
+
 import edu.wpi.first.units.measure.AngularVelocity;
 import edu.wpi.first.units.measure.ImmutableAngularVelocity;
 import edu.wpi.first.units.measure.MutAngularVelocity;
@@ -72,6 +74,24 @@ public MutAngularVelocity mutable(double initialMagnitude) {
     return new MutAngularVelocity(initialMagnitude, toBaseUnits(initialMagnitude), this);
   }
 
+  /**
+   * Constructs a unit of power equivalent to this unit of angular velocity multiplied by another
+   * unit of torque. For example, {@code NewtonMeters.times(RadiansPerSecond)} will return a unit of
+   * power equivalent to one Watt.
+   *
+   * @param torque the unit of torque
+   * @param name the name of the resulting unit of power
+   * @param symbol the symbol used to represent the unit of power
+   * @return the power unit
+   */
+  public PowerUnit mult(TorqueUnit torque, String name, String symbol) {
+    double baseUnitEquivalent = torque.toBaseUnits(1) / this.toBaseUnits(1);
+    UnaryFunction toBaseConverter = x -> x * baseUnitEquivalent;
+    UnaryFunction fromBaseConverter = x -> x / baseUnitEquivalent;
+    PowerUnit powerUnit = new PowerUnit(Watts, toBaseConverter, fromBaseConverter, name, symbol);
+    return Units.derive(powerUnit).named(name).symbol(symbol).make();
+  }
+
   @Override
   public AngularAccelerationUnit per(TimeUnit period) {
     return AngularAccelerationUnit.combine(this, period);

wpiunits/src/main/java/edu/wpi/first/units/BaseUnits.java

@@ -25,15 +25,9 @@ private BaseUnits() {
   /** The standard "unitless" unit. */
   public static final DimensionlessUnit Value = new DimensionlessUnit(null, 1, "<?>", "<?>");
 
-  /** The standard unit of voltage, volts. */
-  public static final VoltageUnit VoltageUnit = new VoltageUnit(null, 1, "Volt", "V");
-
   /** The standard unit of electric current, amperes. */
   public static final CurrentUnit CurrentUnit = new CurrentUnit(null, 1, "Amp", "A");
 
-  /** The standard unit of energy, joules. */
-  public static final EnergyUnit EnergyUnit = new EnergyUnit(null, 1, "Joule", "J");
-
   /** The standard unit of temperature, kelvin. */
   public static final TemperatureUnit TemperatureUnit =
       new TemperatureUnit(null, x -> x, x -> x, "Kelvin", "K");

wpiunits/src/main/java/edu/wpi/first/units/CurrentUnit.java

@@ -4,6 +4,8 @@
 
 package edu.wpi.first.units;
 
+import static edu.wpi.first.units.Units.Watts;
+
 import edu.wpi.first.units.measure.Current;
 import edu.wpi.first.units.measure.ImmutableCurrent;
 import edu.wpi.first.units.measure.MutCurrent;
@@ -43,12 +45,20 @@ public CurrentUnit getBaseUnit() {
    * milliwatt, and so on.
    *
    * @param voltage the voltage unit to multiply by
-   * @param name the name of the resulting unit of power
-   * @param symbol the symbol used to represent the unit of power
    * @return the power unit
    */
-  public PowerUnit mult(VoltageUnit voltage, String name, String symbol) {
-    return Units.derive(PowerUnit.combine(voltage, this)).named(name).symbol(symbol).make();
+  public PowerUnit mult(VoltageUnit voltage) {
+    double baseUnitEquivalent = voltage.toBaseUnits(1) * this.toBaseUnits(1);
+    UnaryFunction toBaseConverter = x -> x * baseUnitEquivalent;
+    UnaryFunction fromBaseConverter = x -> x / baseUnitEquivalent;
+    PowerUnit powerUnit =
+        new PowerUnit(
+            Watts,
+            toBaseConverter,
+            fromBaseConverter,
+            this.name() + "-" + voltage.name(),
+            this.symbol() + "*" + voltage.symbol());
+    return powerUnit;
   }
 
   @Override

wpiunits/src/main/java/edu/wpi/first/units/DistanceUnit.java

@@ -98,5 +98,13 @@ public TorqueUnit multAsTorque(ForceUnit force) {
     return TorqueUnit.combine(this, force);
   }
 
-  // TODO: Add a multAsEnergy equivalent
+  /**
+   * Multiplies this distance unit by a unit of force to create a unit of energy.
+   *
+   * @param force the unit of force
+   * @return the combined energy unit
+   */
+  public EnergyUnit multAsEnergy(ForceUnit force) {
+    return EnergyUnit.combine(force, this);
+  }
 }

wpiunits/src/main/java/edu/wpi/first/units/EnergyUnit.java

@@ -17,7 +17,19 @@
  * <p>Actual units (such as {@link Units#Joules} and {@link Units#Kilojoules}) can be found in the
  * {@link Units} class.
  */
-public final class EnergyUnit extends Unit {
+public final class EnergyUnit extends MultUnit<ForceUnit, DistanceUnit> {
+  private static final CombinatoryUnitCache<ForceUnit, DistanceUnit, EnergyUnit> cache =
+      new CombinatoryUnitCache<>(EnergyUnit::new);
+
+  EnergyUnit(ForceUnit force, DistanceUnit distance) {
+    super(
+        force.isBaseUnit() && distance.isBaseUnit()
+            ? null
+            : combine(force.getBaseUnit(), distance.getBaseUnit()),
+        force,
+        distance);
+  }
+
   EnergyUnit(
       EnergyUnit baseUnit,
       UnaryFunction toBaseConverter,
@@ -27,46 +39,20 @@ public final class EnergyUnit extends Unit {
     super(baseUnit, toBaseConverter, fromBaseConverter, name, symbol);
   }
 
-  EnergyUnit(EnergyUnit baseUnit, double baseUnitEquivalent, String name, String symbol) {
-    super(baseUnit, baseUnitEquivalent, name, symbol);
-  }
-
-  @Override
-  public EnergyUnit getBaseUnit() {
-    return (EnergyUnit) super.getBaseUnit();
-  }
-
-  /**
-   * Combines this unit of energy with a unit of time to create a unit of power.
-   *
-   * @param period the period of the change in energy
-   * @return the combined unit of power
-   */
-  @Override
-  public PowerUnit per(TimeUnit period) {
-    return PowerUnit.combine(this, period);
-  }
-
   /**
-   * Creates a ratio unit between this unit and an arbitrary other unit.
+   * Combines a force and distance to form a unit of energy.
    *
-   * @param other the other unit
-   * @param <U> the type of the other unit
-   * @return the ratio unit
+   * @param force the unit of force
+   * @param distance the unit of distance
+   * @return the combined unit of energy
    */
-  public <U extends Unit> PerUnit<EnergyUnit, U> per(U other) {
-    return PerUnit.combine(this, other);
+  public static EnergyUnit combine(ForceUnit force, DistanceUnit distance) {
+    return cache.combine(force, distance);
   }
 
-  /**
-   * Converts a measurement value in terms of another unit to this unit.
-   *
-   * @param magnitude the magnitude of the measurement in terms of the other unit
-   * @param otherUnit the other unit
-   * @return the value of the measurement in terms of this unit
-   */
-  public double convertFrom(double magnitude, EnergyUnit otherUnit) {
-    return fromBaseUnits(otherUnit.toBaseUnits(magnitude));
+  @Override
+  public EnergyUnit getBaseUnit() {
+    return (EnergyUnit) super.getBaseUnit();
   }
 
   @Override
@@ -89,8 +75,41 @@ public Energy one() {
     return (Energy) super.one();
   }
 
+  /**
+   * Converts a measurement value in terms of another unit to this unit.
+   *
+   * @param magnitude the magnitude of the measurement in terms of the other unit
+   * @param otherUnit the other unit
+   * @return the value of the measurement in terms of this unit
+   */
+  public double convertFrom(double magnitude, EnergyUnit otherUnit) {
+    return fromBaseUnits(otherUnit.toBaseUnits(magnitude));
+  }
+
   @Override
   public MutEnergy mutable(double initialMagnitude) {
     return new MutEnergy(initialMagnitude, toBaseUnits(initialMagnitude), this);
   }
+
+  /**
+   * Combines this unit of energy with a unit of time to create a unit of power.
+   *
+   * @param period the period of the change in energy
+   * @return the combined unit of power
+   */
+  @Override
+  public PowerUnit per(TimeUnit period) {
+    return PowerUnit.combine(this, period);
+  }
+
+  /**
+   * Creates a ratio unit between this unit and an arbitrary other unit.
+   *
+   * @param other the other unit
+   * @param <U> the type of the other unit
+   * @return the ratio unit
+   */
+  public <U extends Unit> PerUnit<EnergyUnit, U> per(U other) {
+    return PerUnit.combine(this, other);
+  }
 }

wpiunits/src/main/java/edu/wpi/first/units/ForceUnit.java

@@ -57,7 +57,15 @@ public TorqueUnit multAsTorque(DistanceUnit distance) {
     return TorqueUnit.combine(distance, this);
   }
 
-  // TODO: Add a multAsEnergy equivalent
+  /**
+   * Multiplies this force unit by a unit of distance to create a unit of energy.
+   *
+   * @param distance the unit of distance
+   * @return the combined energy unit
+   */
+  public EnergyUnit multAsEnergy(DistanceUnit distance) {
+    return EnergyUnit.combine(this, distance);
+  }
 
   @Override
   public Force of(double magnitude) {

wpiunits/src/main/java/edu/wpi/first/units/PowerUnit.java

@@ -4,8 +4,7 @@
 
 package edu.wpi.first.units;
 
-import static edu.wpi.first.units.Units.Joules;
-import static edu.wpi.first.units.Units.Seconds;
+import static edu.wpi.first.units.Units.Amps;
 
 import edu.wpi.first.units.measure.ImmutablePower;
 import edu.wpi.first.units.measure.MutPower;
@@ -53,58 +52,6 @@ public static PowerUnit combine(EnergyUnit energy, TimeUnit period) {
     return cache.combine(energy, period);
   }
 
-  /**
-   * Combines voltage and current into power.
-   *
-   * @param voltage the unit of voltage
-   * @param current the unit of current
-   * @return the combined unit of power
-   */
-  public static PowerUnit combine(VoltageUnit voltage, CurrentUnit current) {
-    return combine(
-        new EnergyUnit(
-            Joules,
-            voltage.toBaseUnits(1) * current.toBaseUnits(1),
-            voltage.name() + "-" + current.name(),
-            voltage.symbol() + "*" + current.symbol()),
-        Seconds);
-  }
-
-  /**
-   * Combines voltage and current into power.
-   *
-   * @param current the unit of current
-   * @param voltage the unit of voltage
-   * @return the combined unit of power
-   */
-  public static PowerUnit combine(CurrentUnit current, VoltageUnit voltage) {
-    return combine(voltage, current);
-  }
-
-  /**
-   * Combines angular velocity and torque into power. Useful when dealing with motors and flywheels.
-   *
-   * @param angularVelocity the unit of angular velocity
-   * @param torque the unit of torque
-   * @return the combined unit of power
-   */
-  public static PowerUnit combine(AngularVelocityUnit angularVelocity, TorqueUnit torque) {
-    return combine(
-        new EnergyUnit(Joules, angularVelocity.toBaseUnits(1) * torque.toBaseUnits(1), "", ""),
-        Seconds);
-  }
-
-  /**
-   * Combines angular velocity and torque into power. Useful when dealing with motors and flywheels.
-   *
-   * @param torque the unit of torque
-   * @param angularVelocity the unit of angular velocity
-   * @return the combined unit of power
-   */
-  public static PowerUnit combine(TorqueUnit torque, AngularVelocityUnit angularVelocity) {
-    return combine(angularVelocity, torque);
-  }
-
   @Override
   public PowerUnit getBaseUnit() {
     return (PowerUnit) super.getBaseUnit();
@@ -135,6 +82,32 @@ public MutPower mutable(double initialMagnitude) {
     return new MutPower(initialMagnitude, toBaseUnits(initialMagnitude), this);
   }
 
+  public VoltageUnit per(CurrentUnit current) {
+    return VoltageUnit.combine(this, current);
+  }
+
+  /**
+   * Constructs a unit of current equivalent to this unit of power divided by another unit of
+   * voltage. For example, {@code Watts.per(Volts)} will return a unit of power equivalent to one
+   * Amp.
+   *
+   * @param voltage the voltage unit to multiply by
+   * @return the power unit
+   */
+  public CurrentUnit per(VoltageUnit voltage) {
+    double baseUnitEquivalent = this.toBaseUnits(1) / voltage.toBaseUnits(1);
+    UnaryFunction toBaseConverter = x -> x * baseUnitEquivalent;
+    UnaryFunction fromBaseConverter = x -> x / baseUnitEquivalent;
+    CurrentUnit currentUnit =
+        new CurrentUnit(
+            Amps,
+            toBaseConverter,
+            fromBaseConverter,
+            this.name() + " per " + voltage.name(),
+            this.symbol() + "/" + voltage.symbol());
+    return Units.derive(currentUnit).make();
+  }
+
   @Override
   public VelocityUnit<PowerUnit> per(TimeUnit time) {
     return VelocityUnit.combine(this, time);

wpiunits/src/main/java/edu/wpi/first/units/TorqueUnit.java

@@ -4,6 +4,8 @@
 
 package edu.wpi.first.units;
 
+import static edu.wpi.first.units.Units.Watts;
+
 import edu.wpi.first.units.measure.ImmutableTorque;
 import edu.wpi.first.units.measure.MutTorque;
 import edu.wpi.first.units.measure.Torque;
@@ -72,6 +74,24 @@ public MutTorque mutable(double initialMagnitude) {
     return new MutTorque(initialMagnitude, toBaseUnits(initialMagnitude), this);
   }
 
+  /**
+   * Constructs a unit of power equivalent to this unit of torque multiplied by another unit of
+   * angular velocity. For example, {@code NewtonMeters.times(RadiansPerSecond)} will return a unit
+   * of power equivalent to one Watt.
+   *
+   * @param angularVelocity the unit of angular velocity
+   * @param name the name of the resulting unit of power
+   * @param symbol the symbol used to represent the unit of power
+   * @return the power unit
+   */
+  public PowerUnit mult(AngularVelocityUnit angularVelocity, String name, String symbol) {
+    double baseUnitEquivalent = this.toBaseUnits(1) / angularVelocity.toBaseUnits(1);
+    UnaryFunction toBaseConverter = x -> x * baseUnitEquivalent;
+    UnaryFunction fromBaseConverter = x -> x / baseUnitEquivalent;
+    PowerUnit powerUnit = new PowerUnit(Watts, toBaseConverter, fromBaseConverter, name, symbol);
+    return Units.derive(powerUnit).named(name).symbol(symbol).make();
+  }
+
   @Override
   public VelocityUnit<TorqueUnit> per(TimeUnit time) {
     return VelocityUnit.combine(this, time);