Variance (GenericNamedArraylist function): Difference between revisions
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{{Template:GenericNamedArraylist:Variance subtitle}} | {{Template:GenericNamedArraylist:Variance subtitle}} | ||
This | This method returns by default the variance of the values of the items in the collection, or it returns the variance of the items after a specified function has been applied to them. | ||
The variance is the "mean standard deviation" of the values of the items in the collection, the average of the squares of the deviations of the value of each item from the mean of all the items. | |||
==Syntax== | ==Syntax== | ||
{{Template:GenericNamedArraylist:Variance syntax}} | {{Template:GenericNamedArraylist:Variance syntax}} | ||
===Syntax terms=== | ===Syntax terms=== | ||
<table class="syntaxTable"> | <table class="syntaxTable"> | ||
<tr><th>%number</th><td> | <tr><th>%number</th> | ||
<td>A <var>Float</var> variable to contain the numeric result.</td></tr> | |||
<tr><th>anyNal</th> | <tr><th>anyNal</th> | ||
<td> | <td>A <var>FloatNamedArraylist</var>, <var>NamedArraylist</var>, or <var>UnicodeNamedArraylist</var> object.</td></tr> | ||
<tr><th>itemFunction</th> | <tr><th>itemFunction</th> | ||
<td><var> | <td>A function that operates on the type of the items in the collection. 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">itemFunction</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">itemFunction</var> parameter lets you further manipulate the collection item values | |||
before calculating the variance. | |||
If your collection 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 an example, see the <var>Arraylist</var> <var>Variance</var> [[Variance (Arraylist function)#Usage notes|"Usage notes"]] section. </p> | |||
</ul> | |||
==Examples== | ==Examples== | ||
<p class="code">b | |||
%nl is namedarrayList of float | |||
%nl = new | |||
%nl('April') = 3000 | |||
%nl('May') = 5000 | |||
%nl('June') = 8000 | |||
[[Targeted Text statements|printText]] {~} is {%nl:variance} | |||
end | |||
</p> | |||
The result is: | |||
<p class="output">%nl:variance is 4222222.22222222 | |||
</p> | |||
==See also== | ==See also== | ||
{{Template:GenericNamedArraylist:Variance footer}} | {{Template:GenericNamedArraylist:Variance footer}} | ||
Latest revision as of 03:26, 8 August 2012
Calculate variance of items or function of items (FloatNamedArraylist, NamedArraylist, and UnicodeNamedArraylist classes)
[Introduced in Sirius Mods 7.8]
This method returns by default the variance of the values of the items in the collection, or it returns the variance of the items after a specified function has been applied to them.
The variance is the "mean standard deviation" of the values of the items in the collection, the average of the squares of the deviations of the value of each item from the mean of all the items.
Syntax
%number = anyNal:Variance[( [itemFunction])]
Syntax terms
| %number | A Float variable to contain the numeric result. |
|---|---|
| anyNal | A FloatNamedArraylist, NamedArraylist, or UnicodeNamedArraylist object. |
| itemFunction | A function that operates on the type of the items in the collection. 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 itemFunction value is the special identity function, This, which simply returns the item value. |
Usage notes
- The optional itemFunction parameter lets you further manipulate the collection item values
before calculating the variance.
If your collection 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 an example, see the Arraylist Variance "Usage notes" section.
Examples
b %nl is namedarrayList of float %nl = new %nl('April') = 3000 %nl('May') = 5000 %nl('June') = 8000 printText {~} is {%nl:variance} end
The result is:
%nl:variance is 4222222.22222222