1 package org.djunits.quantity;
2
3 import org.djunits.quantity.def.Quantity;
4 import org.djunits.unit.AbstractUnit;
5 import org.djunits.unit.UnitRuntimeException;
6 import org.djunits.unit.Unitless;
7 import org.djunits.unit.Units;
8 import org.djunits.unit.scale.LinearScale;
9 import org.djunits.unit.scale.Scale;
10 import org.djunits.unit.si.SIUnit;
11 import org.djunits.unit.system.UnitSystem;
12
13 /**
14 * Areal object density counts the number of objects per unit of area, measured in number per square meter (/m2).
15 * <p>
16 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
17 * for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
18 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
19 * @author Alexander Verbraeck
20 */
21 public class ArealObjectDensity extends Quantity<ArealObjectDensity>
22 {
23 /** Constant with value zero. */
24 public static final ArealObjectDensity ZERO = ArealObjectDensity.ofSi(0.0);
25
26 /** Constant with value one. */
27 public static final ArealObjectDensity ONE = ArealObjectDensity.ofSi(1.0);
28
29 /** Constant with value NaN. */
30 @SuppressWarnings("checkstyle:constantname")
31 public static final ArealObjectDensity NaN = ArealObjectDensity.ofSi(Double.NaN);
32
33 /** Constant with value POSITIVE_INFINITY. */
34 public static final ArealObjectDensity POSITIVE_INFINITY = ArealObjectDensity.ofSi(Double.POSITIVE_INFINITY);
35
36 /** Constant with value NEGATIVE_INFINITY. */
37 public static final ArealObjectDensity NEGATIVE_INFINITY = ArealObjectDensity.ofSi(Double.NEGATIVE_INFINITY);
38
39 /** Constant with value MAX_VALUE. */
40 public static final ArealObjectDensity POS_MAXVALUE = ArealObjectDensity.ofSi(Double.MAX_VALUE);
41
42 /** Constant with value -MAX_VALUE. */
43 public static final ArealObjectDensity NEG_MAXVALUE = ArealObjectDensity.ofSi(-Double.MAX_VALUE);
44
45 /** */
46 private static final long serialVersionUID = 600L;
47
48 /**
49 * Instantiate a ArealObjectDensity quantity with a unit.
50 * @param valueInUnit the value, expressed in the unit
51 * @param unit the unit in which the value is expressed
52 */
53 public ArealObjectDensity(final double valueInUnit, final ArealObjectDensity.Unit unit)
54 {
55 super(valueInUnit, unit);
56 }
57
58 /**
59 * Instantiate a ArealObjectDensity quantity with a unit, expressed as a String.
60 * @param valueInUnit the value, expressed in the unit
61 * @param abbreviation the String abbreviation of the unit in which the value is expressed
62 */
63 public ArealObjectDensity(final double valueInUnit, final String abbreviation)
64 {
65 this(valueInUnit, Units.resolve(ArealObjectDensity.Unit.class, abbreviation));
66 }
67
68 /**
69 * Construct ArealObjectDensity quantity.
70 * @param value Scalar from which to construct this instance
71 */
72 public ArealObjectDensity(final ArealObjectDensity value)
73 {
74 super(value.si(), ArealObjectDensity.Unit.SI);
75 setDisplayUnit(value.getDisplayUnit());
76 }
77
78 /**
79 * Return a ArealObjectDensity instance based on an SI value.
80 * @param si the si value
81 * @return the ArealObjectDensity instance based on an SI value
82 */
83 public static ArealObjectDensity ofSi(final double si)
84 {
85 return new ArealObjectDensity(si, ArealObjectDensity.Unit.SI);
86 }
87
88 @Override
89 public ArealObjectDensity instantiateSi(final double si)
90 {
91 return ofSi(si);
92 }
93
94 @Override
95 public SIUnit siUnit()
96 {
97 return ArealObjectDensity.Unit.SI_UNIT;
98 }
99
100 /**
101 * Returns a ArealObjectDensity representation of a textual representation of a value with a unit. The String representation
102 * that can be parsed is the double value in the unit, followed by a localized or English abbreviation of the unit. Spaces
103 * are allowed, but not required, between the value and the unit.
104 * @param text the textual representation to parse into a ArealObjectDensity
105 * @return the Scalar representation of the value in its unit
106 * @throws IllegalArgumentException when the text cannot be parsed
107 * @throws NullPointerException when the text argument is null
108 */
109 public static ArealObjectDensity valueOf(final String text)
110 {
111 return Quantity.valueOf(text, ZERO);
112 }
113
114 /**
115 * Returns a ArealObjectDensity based on a value and the textual representation of the unit, which can be localized.
116 * @param valueInUnit the value, expressed in the unit as given by unitString
117 * @param unitString the textual representation of the unit
118 * @return the Scalar representation of the value in its unit
119 * @throws IllegalArgumentException when the unit cannot be parsed or is incorrect
120 * @throws NullPointerException when the unitString argument is null
121 */
122 public static ArealObjectDensity of(final double valueInUnit, final String unitString)
123 {
124 return Quantity.of(valueInUnit, unitString, ZERO);
125 }
126
127 @Override
128 public ArealObjectDensity.Unit getDisplayUnit()
129 {
130 return (ArealObjectDensity.Unit) super.getDisplayUnit();
131 }
132
133 /**
134 * Divides this areal object density by another areal object density to yield a dimensionless ratio.
135 * <p>
136 * Formula: (1/m²) / (1/m²) = 1.
137 * @param other the areal object density divisor; must not be {@code null}.
138 * @return the resulting dimensionless ratio in SI (1).
139 * @throws NullPointerException if {@code other} is {@code null}.
140 */
141 public final Dimensionless divide(final ArealObjectDensity other)
142 {
143 return new Dimensionless(this.si() / other.si(), Unitless.BASE);
144 }
145
146 /**
147 * Multiplies this areal object density by an area to yield a dimensionless count.
148 * <p>
149 * Formula: (1/m²) x m² = 1.
150 * @param area the area multiplier; must not be {@code null}.
151 * @return the resulting dimensionless count in SI (1).
152 * @throws NullPointerException if {@code area} is {@code null}.
153 */
154 public final Dimensionless multiply(final Area area)
155 {
156 return new Dimensionless(this.si() * area.si(), Unitless.BASE);
157 }
158
159 /**
160 * Multiplies this areal object density by a length to yield a linear object density.
161 * <p>
162 * Formula: (1/m²) x m = 1/m.
163 * @param length the length multiplier; must not be {@code null}.
164 * @return the resulting linear object density in SI (1/m).
165 * @throws NullPointerException if {@code length} is {@code null}.
166 */
167 public final LinearObjectDensity multiply(final Length length)
168 {
169 return new LinearObjectDensity(this.si() * length.si(), LinearObjectDensity.Unit.SI);
170 }
171
172 /**
173 * Divides this areal object density by a length to yield a volumetric object density.
174 * <p>
175 * Formula: (1/m²) / m = 1/m³.
176 * @param length the length divisor; must not be {@code null}.
177 * @return the resulting volumetric object density in SI (1/m³).
178 * @throws NullPointerException if {@code length} is {@code null}.
179 */
180 public final VolumetricObjectDensity divide(final Length length)
181 {
182 return new VolumetricObjectDensity(this.si() / length.si(), VolumetricObjectDensity.Unit.SI);
183 }
184
185 /**
186 * Divides this areal object density by a volumetric object density to yield a length.
187 * <p>
188 * Formula: (1/m²) / (1/m³) = m.
189 * @param vod the volumetric object density divisor; must not be {@code null}.
190 * @return the resulting length in SI (m).
191 * @throws NullPointerException if {@code vod} is {@code null}.
192 */
193 public final Length divide(final VolumetricObjectDensity vod)
194 {
195 return new Length(this.si() / vod.si(), Length.Unit.SI);
196 }
197
198 @Override
199 public Area reciprocal()
200 {
201 return Area.ofSi(1.0 / this.si());
202 }
203
204 /******************************************************************************************************/
205 /********************************************** UNIT CLASS ********************************************/
206 /******************************************************************************************************/
207
208 /**
209 * ArealObjectDensity.Unit encodes the unit for number of objects per unit of area.
210 * <p>
211 * Copyright (c) 2025-2026 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved.
212 * See for project information <a href="https://djunits.org" target="_blank">https://djunits.org</a>. The DJUNITS project is
213 * distributed under a <a href="https://djunits.org/docs/license.html" target="_blank">three-clause BSD-style license</a>.
214 * @author Alexander Verbraeck
215 */
216 @SuppressWarnings("checkstyle:constantname")
217 public static class Unit extends AbstractUnit<ArealObjectDensity.Unit, ArealObjectDensity>
218 {
219 /** The dimensions of the number of objects per unit of area: per square meter (/m2). */
220 public static final SIUnit SI_UNIT = SIUnit.of("/m2");
221
222 /** per meter. */
223 public static final ArealObjectDensity.Unit per_m2 =
224 new ArealObjectDensity.Unit("/m2", "per square meter", 1.0, UnitSystem.SI_DERIVED);
225
226 /** The SI or BASE unit. */
227 public static final ArealObjectDensity.Unit SI = per_m2;
228
229 /**
230 * Create a new ArealObjectDensity unit.
231 * @param id the id or main abbreviation of the unit
232 * @param name the full name of the unit
233 * @param scaleFactorToBaseUnit the scale factor of the unit to convert it TO the base (SI) unit
234 * @param unitSystem the unit system such as SI or IMPERIAL
235 */
236 public Unit(final String id, final String name, final double scaleFactorToBaseUnit, final UnitSystem unitSystem)
237 {
238 super(id, name, new LinearScale(scaleFactorToBaseUnit), unitSystem);
239 }
240
241 /**
242 * Return a derived unit for this unit, with textual abbreviation(s) and a display abbreviation.
243 * @param textualAbbreviation the textual abbreviation of the unit, which doubles as the id
244 * @param displayAbbreviation the display abbreviation of the unit
245 * @param name the full name of the unit
246 * @param scale the scale to use to convert between this unit and the standard (e.g., SI, BASE) unit
247 * @param unitSystem unit system, e.g. SI or Imperial
248 */
249 public Unit(final String textualAbbreviation, final String displayAbbreviation, final String name, final Scale scale,
250 final UnitSystem unitSystem)
251 {
252 super(textualAbbreviation, displayAbbreviation, name, scale, unitSystem);
253 }
254
255 @Override
256 public SIUnit siUnit()
257 {
258 return SI_UNIT;
259 }
260
261 @Override
262 public Unit getBaseUnit()
263 {
264 return SI;
265 }
266
267 @Override
268 public ArealObjectDensity ofSi(final double si)
269 {
270 return ArealObjectDensity.ofSi(si);
271 }
272
273 @Override
274 public Unit deriveUnit(final String textualAbbreviation, final String displayAbbreviation, final String name,
275 final double scaleFactor, final UnitSystem unitSystem)
276 {
277 if (getScale() instanceof LinearScale ls)
278 {
279 return new ArealObjectDensity.Unit(textualAbbreviation, displayAbbreviation, name,
280 new LinearScale(ls.getScaleFactorToBaseUnit() * scaleFactor), unitSystem);
281 }
282 throw new UnitRuntimeException("Only possible to derive a unit from a unit with a linear scale");
283 }
284
285 }
286 }