FSharp.Charting: Point and Line Charts
Summary: This example shows how to create line and point charts in F#.
A line or a point chart can be created using the Chart.Line
and Chart.Point
methods. When generating a
very large number of points or lines, it is better to use Chart.FastLine
and Chart.FastPoint
. These are special types
of charts that do not support as many visual features but are more efficient.
When using F# Interactive, each of these examples needs to be evaluated separately. This way, F# Interactive
invokes a handler that automatically shows the created chart.
A Simple Line Chart
The following example calls the Chart.Line
method with a list of X and Y values as tuples. The snippet generates
values of a simple function, f(x)=x^2. The values of the function are generated for X ranging from 1 to 100. The chart generated is
shown below.
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// On Mac OSX use FSharp.Charting.Gtk.fsx
#I "packages/FSharp.Charting"
#load "FSharp.Charting.fsx"
open FSharp.Charting
open System

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// Drawing graph of a 'square' function
Chart.Line [ for x in 1.0 .. 100.0 > (x, x ** 2.0) ]

Pipelining into Chart.Line
The following example generates a list containing both X and Y values.
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// Generates 2D curve using list of tuples
let curvyData = [ for i in 0.0 .. 0.02 .. 2.0 * Math.PI > (sin i, cos i * sin i) ]
curvyData > Chart.Line

Specifying only Y values
The following example below shows that you may also simply give a set of Y values, rather than (X,Y) value pairs.
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// Generates 2D curve using only Y values
Chart.Line [ for x in 1.0 .. 100.0 > x * x * sin x ]

It uses a sequence expression ranging
from 0 to 2π with a step size 0.02. This produces a large number of points, so the snippet uses the Chart.Line
method to draw the chart. When using a single list as the data source, it is also possible to elegantly use the pipelining (>
operator).
A Point Chart
The following example shows how to generate a scatter plot. It uses a list to specify the X and Y coordinates of the points.
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// Draw scatter plot of points
let rnd = new Random()
let rand() = rnd.NextDouble()
let randomPoints = [ for i in 0 .. 1000 > rand(), rand() ]

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Chart.Point randomPoints

Specifying Minimums, Maximums and other properties on a Line Chart
The following example shows how to set the name and Y axis minimum properties on the chart and use logdistribution for the X axis.
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let highData = [ for x in 1.0 .. 100.0 > (x, 3000.0 + x ** 2.0) ]
Chart.Line(highData,Name="Rates").WithYAxis(Min=2000.0).WithXAxis(Log=true)

Combining Line Charts
The following example shows how to combine several line charts and give each data set a name. A legend is added
automatically when names are used for data sets.
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let futureDate numDays = DateTime.Today.AddDays(float numDays)
let expectedIncome =
[ for x in 1 .. 100 >
futureDate x, 1000.0 + rand() * 100.0 * exp (float x / 40.0) ]
let expectedExpenses =
[ for x in 1 .. 100 >
futureDate x, rand() * 500.0 * sin (float x / 50.0) ]
let computedProfit =
(expectedIncome, expectedExpenses)
> List.map2 (fun (d1,i) (d2,e) > (d1, i  e))

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Chart.Line(expectedIncome,Name="Income")

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Chart.Line(expectedExpenses,Name="Expenses")

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Chart.Line(computedProfit,Name="Profit")

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Chart.Combine(
[ Chart.Line(expectedIncome,Name="Income")
Chart.Line(expectedExpenses,Name="Expenses")
Chart.Line(computedProfit,Name="Profit") ])
