README.md (6670B)
1 <!-- 2 3 @license Apache-2.0 4 5 Copyright (c) 2018 The Stdlib Authors. 6 7 Licensed under the Apache License, Version 2.0 (the "License"); 8 you may not use this file except in compliance with the License. 9 You may obtain a copy of the License at 10 11 http://www.apache.org/licenses/LICENSE-2.0 12 13 Unless required by applicable law or agreed to in writing, software 14 distributed under the License is distributed on an "AS IS" BASIS, 15 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 See the License for the specific language governing permissions and 17 limitations under the License. 18 19 --> 20 21 # Hypergeometric 22 23 > Hypergeometric distribution constructor. 24 25 <!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. --> 26 27 <section class="intro"> 28 29 </section> 30 31 <!-- /.intro --> 32 33 <!-- Package usage documentation. --> 34 35 <section class="usage"> 36 37 ## Usage 38 39 ```javascript 40 var Hypergeometric = require( '@stdlib/stats/base/dists/hypergeometric/ctor' ); 41 ``` 42 43 #### Hypergeometric( N, K, n ) 44 45 Returns a [hypergeometric][hypergeometric-distribution] distribution object with parameters `N` (population size), `K` (subpopulation size), and `n` (number of draws). 46 47 ```javascript 48 var hypergeometric = new Hypergeometric( 20, 15, 5 ); 49 50 var mu = hypergeometric.mean; 51 // returns 3.75 52 ``` 53 54 * * * 55 56 ## hypergeometric 57 58 A [hypergeometric][hypergeometric-distribution] distribution object has the following properties and methods... 59 60 ### Writable Properties 61 62 #### hypergeometric.N 63 64 Population size of the distribution. `N` **must** be a nonnegative integer that is both larger than or equal to `K` and `n`. 65 66 ```javascript 67 var hypergeometric = new Hypergeometric( 100, 50, 20 ); 68 69 var N = hypergeometric.N; 70 // returns 100.0 71 72 hypergeometric.N = 60; 73 74 N = hypergeometric.N; 75 // returns 60.0 76 ``` 77 78 #### hypergeometric.K 79 80 Subpopulation size of the distribution. `K` **must** be a nonnegative integer that is smaller than or equal to `N`. 81 82 ```javascript 83 var hypergeometric = new Hypergeometric( 100, 50, 20 ); 84 85 var K = hypergeometric.K; 86 // returns 50.0 87 88 hypergeometric.K = 30; 89 90 K = hypergeometric.K; 91 // returns 30.0 92 ``` 93 94 <!--lint disable no-duplicate-headings-in-section --> 95 96 #### hypergeometric.n 97 98 Number of draws of the distribution. `n` **must** be a nonnegative integer that is smaller than or equal to `N`. 99 100 ```javascript 101 var hypergeometric = new Hypergeometric( 100, 50, 20 ); 102 103 var n = hypergeometric.n; 104 // returns 20.0 105 106 hypergeometric.n = 80; 107 108 n = hypergeometric.n; 109 // returns 80.0 110 ``` 111 112 * * * 113 114 ### Computed Properties 115 116 #### Hypergeometric.prototype.kurtosis 117 118 Returns the [excess kurtosis][kurtosis]. 119 120 ```javascript 121 var hypergeometric = new Hypergeometric( 20, 15, 5 ); 122 123 var kurtosis = hypergeometric.kurtosis; 124 // returns ~-0.276 125 ``` 126 127 #### Hypergeometric.prototype.mean 128 129 Returns the [expected value][expected-value]. 130 131 ```javascript 132 var hypergeometric = new Hypergeometric( 20, 15, 5 ); 133 134 var mu = hypergeometric.mean; 135 // returns ~3.75 136 ``` 137 138 #### Hypergeometric.prototype.mode 139 140 Returns the [mode][mode]. 141 142 ```javascript 143 var hypergeometric = new Hypergeometric( 20, 15, 5 ); 144 145 var mode = hypergeometric.mode; 146 // returns 4.0 147 ``` 148 149 #### Hypergeometric.prototype.skewness 150 151 Returns the [skewness][skewness]. 152 153 ```javascript 154 var hypergeometric = new Hypergeometric( 20, 15, 5 ); 155 156 var skewness = hypergeometric.skewness; 157 // returns ~-0.323 158 ``` 159 160 #### Hypergeometric.prototype.stdev 161 162 Returns the [standard deviation][standard-deviation]. 163 164 ```javascript 165 var hypergeometric = new Hypergeometric( 20, 15, 5 ); 166 167 var s = hypergeometric.stdev; 168 // returns ~0.86 169 ``` 170 171 #### Hypergeometric.prototype.variance 172 173 Returns the [variance][variance]. 174 175 ```javascript 176 var hypergeometric = new Hypergeometric( 20, 15, 5 ); 177 178 var s2 = hypergeometric.variance; 179 // returns ~0.74 180 ``` 181 182 * * * 183 184 ### Methods 185 186 #### Hypergeometric.prototype.cdf( x ) 187 188 Evaluates the [cumulative distribution function][cdf] (CDF). 189 190 ```javascript 191 var hypergeometric = new Hypergeometric( 8, 2, 4 ); 192 193 var y = hypergeometric.cdf( 0.5 ); 194 // returns ~0.214 195 ``` 196 197 #### Hypergeometric.prototype.logpmf( x ) 198 199 Evaluates the natural logarithm of the [probability mass function][pmf] (PMF). 200 201 ```javascript 202 var hypergeometric = new Hypergeometric( 8, 2, 4 ); 203 204 var y = hypergeometric.logpmf( 2.0 ); 205 // returns ~-1.54 206 ``` 207 208 #### Hypergeometric.prototype.pmf( x ) 209 210 Evaluates the [probability mass function][pmf] (PMF). 211 212 ```javascript 213 var hypergeometric = new Hypergeometric( 8, 2, 4 ); 214 215 var y = hypergeometric.pmf( 2.0 ); 216 // returns ~0.214 217 ``` 218 219 #### Hypergeometric.prototype.quantile( p ) 220 221 Evaluates the [quantile function][quantile-function] at probability `p`. 222 223 ```javascript 224 var hypergeometric = new Hypergeometric( 8, 2, 4 ); 225 226 var y = hypergeometric.quantile( 0.8 ); 227 // returns 2.0 228 229 y = hypergeometric.quantile( 1.9 ); 230 // returns NaN 231 ``` 232 233 </section> 234 235 <!-- /.usage --> 236 237 <!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> 238 239 <section class="notes"> 240 241 </section> 242 243 <!-- /.notes --> 244 245 <!-- Package usage examples. --> 246 247 * * * 248 249 <section class="examples"> 250 251 ## Examples 252 253 <!-- eslint no-undef: "error" --> 254 255 ```javascript 256 var Hypergeometric = require( '@stdlib/stats/base/dists/hypergeometric/ctor' ); 257 258 var hypergeometric = new Hypergeometric( 100, 50, 20 ); 259 260 var mu = hypergeometric.mean; 261 // returns 10.0 262 263 var mode = hypergeometric.mode; 264 // returns 10.0 265 266 var s2 = hypergeometric.variance; 267 // returns ~4.04 268 269 var y = hypergeometric.cdf( 10.5 ); 270 // returns ~0.598 271 ``` 272 273 </section> 274 275 <!-- /.examples --> 276 277 <!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> 278 279 <section class="references"> 280 281 </section> 282 283 <!-- /.references --> 284 285 <!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> 286 287 <section class="links"> 288 289 [hypergeometric-distribution]: https://en.wikipedia.org/wiki/Hypergeometric_distribution 290 291 [cdf]: https://en.wikipedia.org/wiki/Cumulative_distribution_function 292 293 [pmf]: https://en.wikipedia.org/wiki/Probability_mass_function 294 295 [quantile-function]: https://en.wikipedia.org/wiki/Quantile_function 296 297 [expected-value]: https://en.wikipedia.org/wiki/Expected_value 298 299 [kurtosis]: https://en.wikipedia.org/wiki/Kurtosis 300 301 [mode]: https://en.wikipedia.org/wiki/Mode_%28statistics%29 302 303 [skewness]: https://en.wikipedia.org/wiki/Skewness 304 305 [standard-deviation]: https://en.wikipedia.org/wiki/Standard_deviation 306 307 [variance]: https://en.wikipedia.org/wiki/Variance 308 309 </section> 310 311 <!-- /.links -->