Hi, I'm Keith Battocchi, and I'm working on making it easier to use F# for data-rich programming.  In my first blog post, I want to highlight some of the basic features of the FSharpChart wrappers that Don blogged about earlier this month.  As Don mentioned, this library contains F#-friendly wrappers for the types in the System.Windows.Forms.DataVisualization.Charting namespace, making it easy to interactively chart data from F# Interactive (see also the Chart Controls section of MSDN for further information about the underlying controls themselves, including tutorials).  To get started, load the library script and open the Samples.Charting namespace:

    #load "FSharpChart.fsx"
    open Samples.Charting

Basic features

All of the chart types in the System.Windows.Forms.DataVisualization.Charting namespace are supported, from the common Line and Bar charts to the more exotic Kagi and Renko charts, among many others.  Each type of chart can be created by using static methods on the FSharpChart type, which you can browse in IntelliSense:

These methods make it easy to directly pipe data into a chart.  Furthermore, the FSharpChart library adds a custom printer to F# Interactive which automatically opens each chart control in its own window.  For example, executing 

    [for x in 0.0 .. 0.1 .. 6.0 -> sin x + cos (2.0 * x)]
    |> FSharpChart.Line

in FSI will create the following window:

Each chart control also has a context menu which makes it easy to copy the chart to the clipboard, save to a file, or view (and modify) detailed chart properties:

Series

The overloaded chart creation methods allow data to be specified in many different ways.  In particular, most charts allow data to be specified by any of the following mechanisms:

• Just a sequence of y-values (with x-values implicitly running from 1 to the number of elements, as with the charts above)
• Separate sequences of x- and y-values
• A sequence of (x,y) pairs
• A System.IObservable of y-value or (x,y) pairs, allowing the chart to be updated in real time as additional data is observed

Furthermore, x and y values aren't limited to floating point numbers - they just need to be values of a type implementing the System.IConvertible interface.  This means that it's easy to create charts where data is broken down into named categories:

    [("A",1); ("B",3); ("C",2)]
    |> FSharpChart.Pie

It's equally easy to plot values against dates or times:

    open System
    let r = Random()
    [for d in -30 .. 0 ->
        (DateTime.Today.AddDays(float d), r.NextDouble())]
    |> FSharpChart.Column

Hopefully this is enough information to get you started using the FSharpChart library in F# for interactive visualization.  I'll be writing about some more advanced features in my next blog post.  Until then, happy charting!