Sum (Arraylist function): Difference between revisions
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{{Template:Arraylist:Sum subtitle}} | {{Template:Arraylist:Sum subtitle}} | ||
==Syntax== | ==Syntax== | ||
{{Template:Arraylist:Sum syntax}} | {{Template:Arraylist:Sum syntax}} | ||
===Syntax terms=== | ===Syntax terms=== | ||
<table class="syntaxTable"> | <table class="syntaxTable"> | ||
<tr><th>%sum</th><td> | <tr><th>%sum</th> | ||
<td>A <var>Float</var> variable to contain the numeric result.</td></tr> | |||
<tr><th>al</th> | <tr><th>al</th> | ||
<td>Arraylist object</td></tr> | <td>An <var>Arraylist</var> object.</td></tr> | ||
<tr><th>method</th> | <tr><th>method</th> | ||
<td><var> | <td>A function that operates on the type of the items in the <var>Arraylist</var>. It may be a [[Local and Common entities#Defining and invoking a local method|local method]] or [[Method variables|method variable]] or a class member (<var>Variable</var>, <var>Property</var>), and it must return an [[Intrinsic classes|intrinsic]] (probably <var>Float</var>) value. | ||
<p> | |||
The default <var class="term">method</var> value is the special identity function, <var>This</var>, which simply returns the item value.</p></td></tr> | |||
</table> | </table> | ||
==Usage notes== | ==Usage notes== | ||
<ul> | |||
<li>The optional <var class="term">method</var> parameter lets you further manipulate the <var>Arraylist</var> item values | |||
before performing the <var>Sum</var> method's operation. | |||
If your <var>Arraylist</var>'s items are not intrinsic values, you must specify a function that can map the item values to intrinsic values or the method will fail. | |||
<p> | |||
For example, for an <var>Arraylist</var> that is a list of coordinates, you could | |||
return the sum of their distance from the origin by first applying a local function as the <var>Sum</var> method's <var class="term">method</var> parameter: </p> | |||
<p class="code">b | |||
class point | |||
public | |||
constructor new(%x is float, %y is float) | |||
variable x is float | |||
variable y is float | |||
end public | |||
constructor new(%x is float, %y is float) | |||
%this:x = %x | |||
%this:y = %y | |||
end constructor | |||
end class | |||
local function (point):distance is float | |||
return (%this:x * %this:x + %this:y * %this:y):[[SquareRoot (Float function)|squareRoot]] | |||
end function | |||
%al is arrayList of object point | |||
%al = new | |||
%al:add(new(1,1)) | |||
%al:add(new(3,4)) | |||
%al:add(new(-5,12)) | |||
print %al:sum(distance) | |||
end | |||
</p> | |||
The result is <code>19.4142135623731</code>. </ul> | |||
==Examples== | ==Examples== | ||
<p class="code">b | |||
%al is arrayList of float | |||
%al = new | |||
%al:add(5) | |||
%al:add(3) | |||
%al:add(8) | |||
print %al:sum | |||
end | |||
</p> | |||
The result is: | |||
<p class="output">16 | |||
</p> | |||
==See also== | ==See also== | ||
{{Template:Arraylist:Sum footer}} | {{Template:Arraylist:Sum footer}} | ||
Revision as of 19:16, 10 July 2012
Compute the sum of the items (Arraylist class)
[Introduced in Sirius Mods 7.8]
Syntax
%sum = al:Sum[( [itemFunction])]
Syntax terms
| %sum | A Float variable to contain the numeric result. |
|---|---|
| al | An Arraylist object. |
| method | A function that operates on the type of the items in the Arraylist. It may be a local method or method variable or a class member (Variable, Property), and it must return an intrinsic (probably Float) value.
The default method value is the special identity function, This, which simply returns the item value. |
Usage notes
- The optional method parameter lets you further manipulate the Arraylist item values
before performing the Sum method's operation.
If your Arraylist's items are not intrinsic values, you must specify a function that can map the item values to intrinsic values or the method will fail.
For example, for an Arraylist that is a list of coordinates, you could return the sum of their distance from the origin by first applying a local function as the Sum method's method parameter:
b class point public constructor new(%x is float, %y is float) variable x is float variable y is float end public constructor new(%x is float, %y is float) %this:x = %x %this:y = %y end constructor end class local function (point):distance is float return (%this:x * %this:x + %this:y * %this:y):squareRoot end function %al is arrayList of object point %al = new %al:add(new(1,1)) %al:add(new(3,4)) %al:add(new(-5,12)) print %al:sum(distance) end
The result is19.4142135623731.
Examples
b %al is arrayList of float %al = new %al:add(5) %al:add(3) %al:add(8) print %al:sum end
The result is:
16