StandardDeviation (GenericNamedArraylist function)

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Calculate standard deviation of items or function of items (FloatNamedArraylist, NamedArraylist, and UnicodeNamedArraylist classes)

[Introduced in Sirius Mods 7.8]

This method returns by default the standard deviation of the values of the items in the collection, or the standard deviation after a specified function has been applied to the items.

The standard deviation measures the variation from the mean of the collection items; it is the square root of the collection's variance.


%number = anyNal:StandardDeviation[( [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 standard deviation. 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 StandardDeviation "Usage notes" section.


This request calculates the standard deviation of the items in a NamedArraylist:

b %nl is namedarrayList of float %nl = new %nl('April') = 3000 %nl('May') = 5000 %nl('June') = 8000 printText {~} is {%nl:standardDeviation} end

The result is:

%nl:standardDeviation is 2054.80466765633

See also