Sum (Arraylist function): Difference between revisions

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{{Template:Arraylist:Sum subtitle}}
{{Template:Arraylist:Sum subtitle}}


This page is [[under construction]].
==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>number</td></tr>
<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>ItemFunction</var> object</td></tr>
<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 is 19.4142135623731.

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

See also