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| 1 | +<!-- |
| 2 | +
|
| 3 | +@license Apache-2.0 |
| 4 | +
|
| 5 | +Copyright (c) 2020 The Stdlib Authors. |
| 6 | +
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| 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 | +
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| 11 | + http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | +
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| 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 | +# nanmskrange |
| 22 | + |
| 23 | +> Calculate the [range][range] of a strided array according to a mask, ignoring `NaN` values. |
| 24 | +
|
| 25 | +<section class="intro"> |
| 26 | + |
| 27 | +The [**range**][range] is defined as the difference between the maximum and minimum values. |
| 28 | + |
| 29 | +</section> |
| 30 | + |
| 31 | +<!-- /.intro --> |
| 32 | + |
| 33 | +<section class="usage"> |
| 34 | + |
| 35 | +## Usage |
| 36 | + |
| 37 | +```javascript |
| 38 | +var nanmskrange = require( '@stdlib/stats/strided/nanmskrange' ); |
| 39 | +``` |
| 40 | + |
| 41 | +#### nanmskrange( N, x, strideX, mask, strideMask ) |
| 42 | + |
| 43 | +Computes the [range][range] of a strided array `x` according to a `mask`, ignoring `NaN` values. |
| 44 | + |
| 45 | +```javascript |
| 46 | +var x = [ 1.0, -2.0, 4.0, 2.0, NaN, NaN ]; |
| 47 | +var mask = [ 0, 0, 1, 0, 0, 0 ]; |
| 48 | + |
| 49 | +var v = nanmskrange( 6, x, 1, mask, 1 ); |
| 50 | +// returns 4.0 |
| 51 | +``` |
| 52 | + |
| 53 | +The function has the following parameters: |
| 54 | + |
| 55 | +- **N**: number of indexed elements. |
| 56 | +- **x**: input [`Array`][mdn-array] or [`typed array`][mdn-typed-array]. |
| 57 | +- **strideX**: stride length for `x`. |
| 58 | +- **mask**: mask [`Array`][mdn-array] or [`typed array`][mdn-typed-array]. If a `mask` array element is `0`, the corresponding element in `x` is considered valid and **included** in computation. If a `mask` array element is `1`, the corresponding element in `x` is considered invalid/missing and **excluded** from computation. |
| 59 | +- **strideMask**: stride length for `mask`. |
| 60 | + |
| 61 | +The `N` and stride parameters determine which elements in the strided arrays are accessed at runtime. For example, to compute the [range][range] of every other element in `x`, |
| 62 | + |
| 63 | +```javascript |
| 64 | +var x = [ 1.0, 2.0, -7.0, -2.0, 4.0, 3.0, 5.0, 6.0 ]; |
| 65 | +var mask = [ 0, 0, 0, 0, 0, 0, 1, 1 ]; |
| 66 | + |
| 67 | +var v = nanmskrange( 4, x, 2, mask, 2 ); |
| 68 | +// returns 11.0 |
| 69 | +``` |
| 70 | + |
| 71 | +Note that indexing is relative to the first index. To introduce offsets, use [`typed array`][mdn-typed-array] views. |
| 72 | + |
| 73 | +<!-- eslint-disable stdlib/capitalized-comments, max-len --> |
| 74 | + |
| 75 | +```javascript |
| 76 | +var Float64Array = require( '@stdlib/array/float64' ); |
| 77 | +var Uint8Array = require( '@stdlib/array/uint8' ); |
| 78 | + |
| 79 | +var x0 = new Float64Array( [ 2.0, 1.0, -2.0, -2.0, 3.0, 4.0, 5.0, 6.0, NaN, NaN ] ); |
| 80 | +var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element |
| 81 | + |
| 82 | +var mask0 = new Uint8Array( [ 0, 0, 0, 0, 0, 0, 1, 1, 0, 0 ] ); |
| 83 | +var mask1 = new Uint8Array( mask0.buffer, mask0.BYTES_PER_ELEMENT*1 ); // start at 2nd element |
| 84 | + |
| 85 | +var v = nanmskrange( 5, x1, 2, mask1, 2 ); |
| 86 | +// returns 6.0 |
| 87 | +``` |
| 88 | + |
| 89 | +#### nanmskrange.ndarray( N, x, strideX, offsetX, mask, strideMask, offsetMask ) |
| 90 | + |
| 91 | +Computes the [range][range] of a strided array according to a `mask`, ignoring `NaN` values and using alternative indexing semantics. |
| 92 | + |
| 93 | +```javascript |
| 94 | +var x = [ 1.0, -2.0, 4.0, 2.0, NaN, NaN ]; |
| 95 | +var mask = [ 0, 0, 1, 0, 0, 0 ]; |
| 96 | + |
| 97 | +var v = nanmskrange.ndarray( 6, x, 1, 0, mask, 1, 0 ); |
| 98 | +// returns 4.0 |
| 99 | +``` |
| 100 | + |
| 101 | +The function has the following additional parameters: |
| 102 | + |
| 103 | +- **offsetX**: starting index for `x`. |
| 104 | +- **offsetMask**: starting index for `mask`. |
| 105 | + |
| 106 | +While [`typed array`][mdn-typed-array] views mandate a view offset based on the underlying buffer, the offset parameters support indexing semantics based on a starting indices. For example, to calculate the [range][range] for every other value in `x` starting from the second value |
| 107 | + |
| 108 | +```javascript |
| 109 | +var x = [ 2.0, 1.0, -2.0, -2.0, 3.0, 4.0, 5.0, 6.0 ]; |
| 110 | +var mask = [ 0, 0, 0, 0, 0, 0, 1, 1 ]; |
| 111 | + |
| 112 | +var v = nanmskrange.ndarray( 4, x, 2, 1, mask, 2, 1 ); |
| 113 | +// returns 6.0 |
| 114 | +``` |
| 115 | + |
| 116 | +</section> |
| 117 | + |
| 118 | +<!-- /.usage --> |
| 119 | + |
| 120 | +<section class="notes"> |
| 121 | + |
| 122 | +## Notes |
| 123 | + |
| 124 | +- If `N <= 0`, both functions return `NaN`. |
| 125 | +- Both functions support array-like objects having getter and setter accessors for array element access (e.g., [`@stdlib/array/base/accessor`][@stdlib/array/base/accessor]). |
| 126 | +- Depending on the environment, the typed versions ([`dnanmskrange`][@stdlib/stats/strided/dnanmskrange], [`snanmskrange`][@stdlib/stats/strided/snanmskrange], etc.) are likely to be significantly more performant. |
| 127 | + |
| 128 | +</section> |
| 129 | + |
| 130 | +<!-- /.notes --> |
| 131 | + |
| 132 | +<section class="examples"> |
| 133 | + |
| 134 | +## Examples |
| 135 | + |
| 136 | +<!-- eslint no-undef: "error" --> |
| 137 | + |
| 138 | +```javascript |
| 139 | +var uniform = require( '@stdlib/random/base/uniform' ); |
| 140 | +var bernoulli = require( '@stdlib/random/base/bernoulli' ); |
| 141 | +var filledarrayBy = require( '@stdlib/array/filled-by' ); |
| 142 | +var nanmskrange = require( '@stdlib/stats/strided/nanmskrange' ); |
| 143 | + |
| 144 | +function rand() { |
| 145 | + if ( bernoulli( 0.8 ) < 1 ) { |
| 146 | + return NaN; |
| 147 | + } |
| 148 | + return uniform( -50.0, 50.0 ); |
| 149 | +} |
| 150 | + |
| 151 | +var x = filledarrayBy( 10, 'float64', rand ); |
| 152 | +console.log( x ); |
| 153 | + |
| 154 | +var mask = filledarrayBy( x.length, 'uint8', bernoulli.factory( 0.2 ) ); |
| 155 | +console.log( mask ); |
| 156 | + |
| 157 | +var v = nanmskrange( x.length, x, 1, mask, 1 ); |
| 158 | +console.log( v ); |
| 159 | +``` |
| 160 | + |
| 161 | +</section> |
| 162 | + |
| 163 | +<!-- /.examples --> |
| 164 | + |
| 165 | +<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. --> |
| 166 | + |
| 167 | +<section class="related"> |
| 168 | + |
| 169 | +* * * |
| 170 | + |
| 171 | +## See Also |
| 172 | + |
| 173 | +- <span class="package-name">[`@stdlib/stats/strided/dnanmskrange`][@stdlib/stats/strided/dnanmskrange]</span><span class="delimiter">: </span><span class="description">calculate the range of a double-precision floating-point strided array according to a mask, ignoring NaN values.</span> |
| 174 | +- <span class="package-name">[`@stdlib/stats/strided/mskrange`][@stdlib/stats/strided/mskrange]</span><span class="delimiter">: </span><span class="description">calculate the range of a strided array according to a mask.</span> |
| 175 | +- <span class="package-name">[`@stdlib/stats/base/nanrange`][@stdlib/stats/base/nanrange]</span><span class="delimiter">: </span><span class="description">calculate the range of a strided array, ignoring NaN values.</span> |
| 176 | +- <span class="package-name">[`@stdlib/stats/base/nanmskmax`][@stdlib/stats/base/nanmskmax]</span><span class="delimiter">: </span><span class="description">calculate the maximum value of a strided array according to a mask, ignoring NaN values.</span> |
| 177 | +- <span class="package-name">[`@stdlib/stats/base/nanmskmin`][@stdlib/stats/base/nanmskmin]</span><span class="delimiter">: </span><span class="description">calculate the minimum value of a strided array according to a mask, ignoring NaN values.</span> |
| 178 | +- <span class="package-name">[`@stdlib/stats/strided/snanmskrange`][@stdlib/stats/strided/snanmskrange]</span><span class="delimiter">: </span><span class="description">calculate the range of a single-precision floating-point strided array according to a mask, ignoring NaN values.</span> |
| 179 | + |
| 180 | +</section> |
| 181 | + |
| 182 | +<!-- /.related --> |
| 183 | + |
| 184 | +<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. --> |
| 185 | + |
| 186 | +<section class="links"> |
| 187 | + |
| 188 | +[range]: https://en.wikipedia.org/wiki/Range_%28statistics%29 |
| 189 | + |
| 190 | +[mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array |
| 191 | + |
| 192 | +[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray |
| 193 | + |
| 194 | +[@stdlib/array/base/accessor]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/array/base/accessor |
| 195 | + |
| 196 | +<!-- <related-links> --> |
| 197 | + |
| 198 | +[@stdlib/stats/strided/dnanmskrange]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/dnanmskrange |
| 199 | + |
| 200 | +[@stdlib/stats/strided/mskrange]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/mskrange |
| 201 | + |
| 202 | +[@stdlib/stats/base/nanrange]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/base/nanrange |
| 203 | + |
| 204 | +[@stdlib/stats/base/nanmskmax]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/base/nanmskmax |
| 205 | + |
| 206 | +[@stdlib/stats/base/nanmskmin]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/base/nanmskmin |
| 207 | + |
| 208 | +[@stdlib/stats/strided/snanmskrange]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/stats/strided/snanmskrange |
| 209 | + |
| 210 | +<!-- </related-links> --> |
| 211 | + |
| 212 | +</section> |
| 213 | + |
| 214 | +<!-- /.links --> |
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