@mapgis/webclient-common

<header id="page-title" class="page-title"> <span class="page-title-main">类名</span> <span class="page-title-sub">表达式</span> </header> <section> <header> </header> <article> <h2>表达式说明</h2> <p>目前表达式支持的功能</p> <ul> <li> <p>链接符</p> </li> <li> <p>数学运算符</p> </li> <li> <p>条件运算符</p> </li> </ul> <h4>链接符</h4> <p>目前仅支持$feature链接符，支持访问要素的属性信息。 <strong>example</strong></p> <pre class="prettyprint source"><code>$feature.FID //表示访问要素的FID字段 </code></pre> <h4><strong>数学运算</strong></h4> <p>支持一般通用数学运算符，如+-*/等计算符</p> <p><strong>example</strong></p> <p>计算面积占比</p> <pre class="prettyprint source"><code>$feature.AREA/$feature.TOTALAREA </code></pre> <h4><strong>条件运算</strong></h4> <p><strong>example</strong></p> <p>支持 || and or >= <=等</p> <pre class="prettyprint source"><code>$feature.ISAREA || $feature.ISRIVER </code></pre> <h3>后续拟支持的表达式运算符和内置函数</h3> <h4>Operator Precedence</h4> <table> <thead> <tr> <th style="text-align:left">Operator</th> <th style="text-align:left">Associativity</th> <th style="text-align:left">Description</th> </tr> </thead> <tbody> <tr> <td style="text-align:left">(...)</td> <td style="text-align:left">None</td> <td style="text-align:left">Grouping</td> </tr> <tr> <td style="text-align:left">f(), x.y, a[i]</td> <td style="text-align:left">Left</td> <td style="text-align:left">Function call, property access, array indexing</td> </tr> <tr> <td style="text-align:left">!</td> <td style="text-align:left">Left</td> <td style="text-align:left">Factorial</td> </tr> <tr> <td style="text-align:left">^</td> <td style="text-align:left">Right</td> <td style="text-align:left">Exponentiation</td> </tr> <tr> <td style="text-align:left">+, -, not, sqrt, etc.</td> <td style="text-align:left">Right</td> <td style="text-align:left">Unary prefix operators (see below for the full list)</td> </tr> <tr> <td style="text-align:left">*, /, %</td> <td style="text-align:left">Left</td> <td style="text-align:left">Multiplication, division, remainder</td> </tr> <tr> <td style="text-align:left">+, -, ||</td> <td style="text-align:left">Left</td> <td style="text-align:left">Addition, subtraction, array/list concatenation</td> </tr> <tr> <td style="text-align:left">==, !=, >=, <=, >, <, in</td> <td style="text-align:left">Left</td> <td style="text-align:left">Equals, not equals, etc. "in" means "is the left operand included in the right array operand?"</td> </tr> <tr> <td style="text-align:left">and</td> <td style="text-align:left">Left</td> <td style="text-align:left">Logical AND</td> </tr> <tr> <td style="text-align:left">or</td> <td style="text-align:left">Left</td> <td style="text-align:left">Logical OR</td> </tr> <tr> <td style="text-align:left">x ? y : z</td> <td style="text-align:left">Right</td> <td style="text-align:left">Ternary conditional (if x then y else z)</td> </tr> <tr> <td style="text-align:left">=</td> <td style="text-align:left">Right</td> <td style="text-align:left">Variable assignment</td> </tr> <tr> <td style="text-align:left">;</td> <td style="text-align:left">Left</td> <td style="text-align:left">Expression separator</td> </tr> </tbody> </table> <h4>Unary operators</h4> <table> <thead> <tr> <th style="text-align:left">Operator</th> <th style="text-align:left">Description</th> </tr> </thead> <tbody> <tr> <td style="text-align:left">-x</td> <td style="text-align:left">Negation</td> </tr> <tr> <td style="text-align:left">+x</td> <td style="text-align:left">Unary plus. This converts it's operand to a number, but has no other effect.</td> </tr> <tr> <td style="text-align:left">x!</td> <td style="text-align:left">Factorial (x * (x-1) * (x-2) * … * 2 * 1). gamma(x + 1) for non-integers.</td> </tr> <tr> <td style="text-align:left">abs x</td> <td style="text-align:left">Absolute value (magnitude) of x</td> </tr> <tr> <td style="text-align:left">acos x</td> <td style="text-align:left">Arc cosine of x (in radians)</td> </tr> <tr> <td style="text-align:left">acosh x</td> <td style="text-align:left">Hyperbolic arc cosine of x (in radians)</td> </tr> <tr> <td style="text-align:left">asin x</td> <td style="text-align:left">Arc sine of x (in radians)</td> </tr> <tr> <td style="text-align:left">asinh x</td> <td style="text-align:left">Hyperbolic arc sine of x (in radians)</td> </tr> <tr> <td style="text-align:left">atan x</td> <td style="text-align:left">Arc tangent of x (in radians)</td> </tr> <tr> <td style="text-align:left">atanh x</td> <td style="text-align:left">Hyperbolic arc tangent of x (in radians)</td> </tr> <tr> <td style="text-align:left">cbrt x</td> <td style="text-align:left">Cube root of x</td> </tr> <tr> <td style="text-align:left">ceil x</td> <td style="text-align:left">Ceiling of x — the smallest integer that’s >= x</td> </tr> <tr> <td style="text-align:left">cos x</td> <td style="text-align:left">Cosine of x (x is in radians)</td> </tr> <tr> <td style="text-align:left">cosh x</td> <td style="text-align:left">Hyperbolic cosine of x (x is in radians)</td> </tr> <tr> <td style="text-align:left">exp x</td> <td style="text-align:left">e^x (exponential/antilogarithm function with base e)</td> </tr> <tr> <td style="text-align:left">expm1 x</td> <td style="text-align:left">e^x - 1</td> </tr> <tr> <td style="text-align:left">floor x</td> <td style="text-align:left">Floor of x — the largest integer that’s <= x</td> </tr> <tr> <td style="text-align:left">length x</td> <td style="text-align:left">String length of x</td> </tr> <tr> <td style="text-align:left">ln x</td> <td style="text-align:left">Natural logarithm of x</td> </tr> <tr> <td style="text-align:left">log x</td> <td style="text-align:left">Natural logarithm of x (synonym for ln, not base-10)</td> </tr> <tr> <td style="text-align:left">log10 x</td> <td style="text-align:left">Base-10 logarithm of x</td> </tr> <tr> <td style="text-align:left">log2 x</td> <td style="text-align:left">Base-2 logarithm of x</td> </tr> <tr> <td style="text-align:left">log1p x</td> <td style="text-align:left">Natural logarithm of (1 + x)</td> </tr> <tr> <td style="text-align:left">not x</td> <td style="text-align:left">Logical NOT operator</td> </tr> <tr> <td style="text-align:left">round x</td> <td style="text-align:left">X, rounded to the nearest integer, using "grade-school rounding"</td> </tr> <tr> <td style="text-align:left">sign x</td> <td style="text-align:left">Sign of x (-1, 0, or 1 for negative, zero, or positive respectively)</td> </tr> <tr> <td style="text-align:left">sin x</td> <td style="text-align:left">Sine of x (x is in radians)</td> </tr> <tr> <td style="text-align:left">sinh x</td> <td style="text-align:left">Hyperbolic sine of x (x is in radians)</td> </tr> <tr> <td style="text-align:left">sqrt x</td> <td style="text-align:left">Square root of x. Result is NaN (Not a Number) if x is negative.</td> </tr> <tr> <td style="text-align:left">tan x</td> <td style="text-align:left">Tangent of x (x is in radians)</td> </tr> <tr> <td style="text-align:left">tanh x</td> <td style="text-align:left">Hyperbolic tangent of x (x is in radians)</td> </tr> <tr> <td style="text-align:left">trunc x</td> <td style="text-align:left">Integral part of a X, looks like floor(x) unless for negative number</td> </tr> </tbody> </table> <h4>Pre-defined functions</h4> <table> <thead> <tr> <th style="text-align:left">Function</th> <th style="text-align:left">Description</th> </tr> </thead> <tbody> <tr> <td style="text-align:left">random(n)</td> <td style="text-align:left">Get a random number in the range [0, n). If n is zero, or not provided, it defaults to 1.</td> </tr> <tr> <td style="text-align:left">fac(n)</td> <td style="text-align:left">n! (factorial of n: "n * (n-1) * (n-2) * … * 2 * 1") Deprecated. Use the ! operator instead.</td> </tr> <tr> <td style="text-align:left">min(a,b,…)</td> <td style="text-align:left">Get the smallest (minimum) number in the list.</td> </tr> <tr> <td style="text-align:left">max(a,b,…)</td> <td style="text-align:left">Get the largest (maximum) number in the list.</td> </tr> <tr> <td style="text-align:left">hypot(a,b)</td> <td style="text-align:left">Hypotenuse, i.e. the square root of the sum of squares of its arguments.</td> </tr> <tr> <td style="text-align:left">pyt(a, b)</td> <td style="text-align:left">Alias for hypot.</td> </tr> <tr> <td style="text-align:left">pow(x, y)</td> <td style="text-align:left">Equivalent to x^y. For consistency with JavaScript's Math object.</td> </tr> <tr> <td style="text-align:left">atan2(y, x)</td> <td style="text-align:left">Arc tangent of x/y. i.e. the angle between (0, 0) and (x, y) in radians.</td> </tr> <tr> <td style="text-align:left">roundTo(x, n)</td> <td style="text-align:left">Rounds x to n places after the decimal point.</td> </tr> <tr> <td style="text-align:left">map(f, a)</td> <td style="text-align:left">Array map: Pass each element of <code>a</code> the function <code>f</code>, and return an array of the results.</td> </tr> <tr> <td style="text-align:left">fold(f, y, a)</td> <td style="text-align:left">Array fold: Fold/reduce array <code>a</code> into a single value, <code>y</code> by setting <code>y = f(y, x, index)</code> for each element <code>x</code> of the array.</td> </tr> <tr> <td style="text-align:left">filter(f, a)</td> <td style="text-align:left">Array filter: Return an array containing only the values from <code>a</code> where <code>f(x, index)</code> is <code>true</code>.</td> </tr> <tr> <td style="text-align:left">indexOf(x, a)</td> <td style="text-align:left">Return the first index of string or array <code>a</code> matching the value <code>x</code>, or <code>-1</code> if not found.</td> </tr> <tr> <td style="text-align:left">join(sep, a)</td> <td style="text-align:left">Concatenate the elements of <code>a</code>, separated by <code>sep</code>.</td> </tr> <tr> <td style="text-align:left">if(c, a, b)</td> <td style="text-align:left">Function form of c ? a : b. Note: This always evaluates both <code>a</code> and <code>b</code>, regardless of whether <code>c</code> is <code>true</code> or not. Use <code>c ? a : b</code> instead if there are side effects, or if evaluating the branches could be expensive.</td> </tr> <tr> <td style="text-align:left">when(case,value,case,value,defaultValue)</td> <td style="text-align:left">条件语句</td> </tr> </tbody> </table> </article> </section>