The custom calculation formula language is based on VB and can be extended with LINQ. You can at any time write your formula in LINQ if you are not able to perform your calculations with the pre-defined functions.
Below is a list of some useful LINQ expressions. This is not exhaustive. Please refer to Microsoft Visual basic LINQ documentation for more details.
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The principle of filters is to filter a given list of items according to a predicate. To apply filter, you need:
a list to filter
a predicate (function taking a list item and returning a boolean)
The result is a new list with some of the items of input list.
The number of items in the new list is smaller than in the input list. |
Syntax:
InputList.Where(Function(x) predicate)
Where: to call the filter
Function: to write the predicate
Example:
CurrentSignal.AllPeaks.Where(Function(p) p.Peak_Area>1.2 and p.Peak_Height<1000) returns a list of peaks with an area greater than 1.2 and height lower than 1000.
You can use this list in a formula to do the sum of the areas of all peaks in the list:
Sum("Peak_Area", CurrentSignal.AllPeaks.Where(Function(p) p.Peak_Area>1.2 And p.Peak_Height<1000))
The principle of projection is to create a list from a given list of items by transforming every item. To apply projection, you need:
A list to transform
A projection function (function taking a list item and returning a new item)
| The result is a new list of same length as input list. Item types can be different! |
Syntax:
InputList.Select(Function(x) projection)
Select: to call the transformation
Function: to write the projection function
Example:
CurrentSignal.AllPeaks.Select(Function(p) p.Peak_Area) returns a list of Peak_Area values from a list of peaks.
You can then do the sum: CurrentSignal.AllPeaks.Select(Function(p) p.Peak_Area).Sum()
Note that this is equivalent to the predefined Custom Calculation function Sum(“Peak_Area”, CurrentSignal.AllPeaks).
The principle of aggregate is to compute a single value from a list. To apply aggregation, you need:
InputList.Select(Function(x) projection)
A list to aggregate
An accumulation function (function taking aggregate and current item)
An initial value for aggregate
The result is a unique aggregated value. The type of aggregated value can be different from item type. |
Syntax:
InputList.Aggregate(initial value,Function(acc,x) accumulation)
Aggregate: to call the aggregation
Function: to write the accumulation function
Examples:
(CurrentSignal.AllPeaks.Select(Function(p) p.Peak_Area)).Aggregate("", Function(acc,x) acc+" ; "&x) returns the list of all peaks area separated with a " ; ".
Note that this is equivalent to a VB function: string.join(" ; " ,CurrentSignal.AllPeaks.Select(Function(p) p.Peak_Area)).
(CurrentSignal.AllPeaks.Select(Function(p) p.Peak_Area)).Aggregate(0.0, Function(acc,x) acc+x) returns the sum of the peak areas.
Note that it is equivalent to the predefined Custom Calculation function Sum("Peak_Area", CurrentSignal.AllPeaks).