我想使用内置功能或免费库在 F# 中制作一些基本图表。 如果可能的话，我会非常高兴有一个非常基本的例子，一个饼图。
示例数据：
[("John",34);("Sara",30);("Will",20);("Maria",16)]
整数是要在饼图中表示的百分比。
我最近安装了 VSLab，虽然我找到了很多 3D 示例，但我只是在寻找一个简单的饼图...
顺便用excel功能也不错，不是免费的，不过还是安装好了..
【问题讨论】：
这是我使用 Google Chart API 拼凑起来的东西， 我希望代码足够清晰，无需进一步解释：
//Built with F# 1.9.7.8
open System.IO
open System.Net
open Microsoft.FSharp.Control.WebExtensions
//Add references for the namespaces below if you're not running this code in F# interactive
open System.Drawing
open System.Windows.Forms
let buildGoogleChartUri input =
let chartWidth, chartHeight = 250,100
let labels,data = List.unzip input
let dataString =
data
|> List.map (box>>string) //in this way, data can be anything for which ToString() turns it into a number
|> List.toArray |> String.concat ","
let labelString = labels |> List.toArray |> String.concat "|"
sprintf "http://chart.apis.google.com/chart?chs=%dx%d&chd=t:%s&cht=p3&chl=%s"
chartWidth chartHeight dataString labelString
//Bake a bitmap from the google chart URI
let buildGoogleChart myData =
async {
let req = HttpWebRequest.Create(buildGoogleChartUri myData)
let! response = req.AsyncGetResponse()
return new Bitmap(response.GetResponseStream())
} |> Async.RunSynchronously
//invokes the google chart api to build a chart from the data, and presents the image in a form
//Excuse the sloppy winforms code
let test() =
let myData = [("John",34);("Sara",30);("Will",20);("Maria",16)]
let image = buildGoogleChart myData
let frm = new Form()
frm.BackgroundImage <- image
frm.BackgroundImageLayout <- ImageLayout.Center
frm.ClientSize <- image.Size
frm.Show()
【讨论】：
制作“自制”饼图很容易： 打开 System.Drawing
let red = new SolidBrush(Color.Red) in
let green = new SolidBrush(Color.Green) in
let blue = new SolidBrush(Color.Blue) in
let rec colors =
seq {
yield red
yield green
yield blue
yield! colors
}
let pie data (g: Graphics) (r: Rectangle) =
let vals = 0.0 :: List.map snd data
let total = List.sum vals
let angles = List.map (fun v -> v/total*360.0) vals
let p = new Pen(Color.Black,1)
Seq.pairwise vals |> Seq.zip colors |> Seq.iter (fun (c,(a1,a2)) -> g.DrawPie(p,r,a1,a2); g.FillPie(c,r,a1,a2))
【讨论】：
老问题，但技术正在改变。
在 vs 2013、F# 3 中，并安装 nuget 包
Install-Package FSharp.Charting
添加引用：
System.Windows.Forms
System.Windows.Forms.DataVisualization
只需要一行代码：
Application.Run ((Chart.Pie data).ShowChart())
以下 F# 代码生成饼图：
open System
open System.Windows.Forms
open FSharp.Charting
[<EntryPoint>]
let main argv =
Application.EnableVisualStyles()
Application.SetCompatibleTextRenderingDefault false
let data =[("John",34);("Sara",30);("Will",20);("Maria",16)]
Application.Run ((Chart.Pie data).ShowChart())
0
你会得到下面的图表：
【讨论】：
最初我只是尝试用一个非常简单的显示饼图的窗体对话框来补充 ssp 的 示例。但是尝试这个我在 ssp 的代码中发现了一个错误：一方面Seq.pairwise 在vals 而不是angles 上运行，另一方面它显然不认为饼片将从起始角度开始绘制后掠角。
我更正了错误、注释、重新排列、重新格式化和重命名了一些内容 - 并使其在 fsi.exe 和 可编译 中的 #load-able 和 >fsc.exe:
#light
module YourNamespace.PieExample
open System
open System.Drawing
open System.ComponentModel
open System.Windows.Forms
(* (circular) sequence of three colors *)
#nowarn "40"
let red = new SolidBrush(Color.Red)
let green = new SolidBrush(Color.Green)
let blue = new SolidBrush(Color.Blue)
let rec colors =
seq { yield red
yield green
yield blue
yield! colors }
(* core function to build up and show a pie diagram *)
let pie data (g: Graphics) (r: Rectangle) =
// a pen for borders of pie slices
let p = new Pen(Color.Black, 1.0f)
// retrieve pie shares from data and sum 'em up
let vals = List.map snd data
let total = List.sum vals
// baking a pie starts here with ...
vals
// scaling vals in total to a full circle
|> List.map (fun v -> v * 360.0 / total)
// transform list of angles to list of pie slice delimiting angles
|> List.scan (+) 0.0
// turn them into a list of tuples consisting of start and end angles
|> Seq.pairwise
// intermix the colors successively
|> Seq.zip colors
// and at last do FillPies and DrawPies with these ingredients
|> Seq.iter (fun (c,(starta,enda))
-> g.FillPie(c,r,(float32 starta)
,(float32 (enda - starta)))
g.DrawPie(p,r,(float32 starta)
,(float32 (enda - starta))))
(* demo data *)
let demolist = [ ("a", 1.); ("b", 2.); ("c", 3.);
("d", 2.); ("e", 2.); ("f", 2.) ]
(* finally a simple resizable form showing demo data as pie with 6 slices *)
let mainform = new Form(MinimumSize = Size(200,200))
// add two event handlers
mainform.Paint.Add (fun e -> pie demolist e.Graphics mainform.ClientRectangle)
mainform.Resize.Add (fun _ -> mainform.Invalidate())
#if COMPILED
Application.Run(mainform)
#else
mainform.ShowDialog() |> ignore
#endif
最后但同样重要的是，我想提两个我发现有用的提示
List.scan 的用法
【讨论】：