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Worf

TypeScript, VBA, and the Graham Scan

Excel Version
  1. 365
Typescript is the language of Excel scripts, available at certain Office 365 licenses. Unfortunately, my company chose to disable this feature, so at this time I cannot use it.
However, we can write TS outside of Excel. This article shows how to output TS data to a text file that Excel can read.
The code finds the convex hull for a bidimensional set of points; read more about the Graham algorithm in the link below.
Here are the main features of this project:

  • The points can be code generated or read from file.
  • The results are written to a text file so that they can be retrieved by other applications.
  • I used Visual Studio to edit the TS code, the TS Compiler to generate the corresponding JavaScript and finally Node to run it.
  • A VBA macro imports the data and creates a chart to visually represent the solution.

graham.png


VBA Code:
Sub Graham()
Dim ob As Shape, rng As Range, sht As Worksheet, lr%, fp%
Workbooks.OpenText Filename:="C:\Users\en_sa\helloworld\example.txt", Origin _
:=xlMSDOS, StartRow:=1, DataType:=xlDelimited, TextQualifier:= _
xlDoubleQuote, ConsecutiveDelimiter:=False, Tab:=True, Semicolon:=False, _
Comma:=False, Space:=False, Other:=False, FieldInfo:=Array(Array(1, 1), _
Array(2, 1)), TrailingMinusNumbers:=True
Set sht = ActiveSheet
Set rng = sht.Columns("a:a").Find("end", LookIn:=xlValues)
fp = Split(rng.Address, "$")(2)
lr = Evaluate("=MAX((B:B<>"""")*(ROW(B:B)))")
Range(Cells(fp + 1, 1), Cells(fp + 1, 2)).Copy Cells(lr + 1, 1)
Set ob = sht.Shapes.AddChart2(240, xlXYScatterLines)
ob.Chart.SetSourceData Source:=Range("example!$A$1:$B$" & (fp - 1))
Application.CutCopyMode = False
ob.Chart.SeriesCollection.NewSeries
With ob.Chart.FullSeriesCollection(2)
    .Name = "=""sec"""
    .XValues = "=example!$A$" & (fp + 1) & ":$A$" & lr + 1
    .Values = "=example!$B$" & (fp + 1) & ":$B$" & lr + 1
    .ChartType = xlXYScatterLines
End With
With ob.Chart
    .FullSeriesCollection(1).ChartType = xlXYScatter
    .Axes(xlValue).MinimumScale = -1
    .Axes(xlCategory).MaximumScale = 11
    .HasTitle = False
End With
End Sub

JavaScript:
interface point {
    x:number
    y:number
    angle:number
    discarded:boolean
    zero:boolean
}
import { readFileSync, writeFileSync } from 'fs';
import { join } from 'path';
let st=""
let xarr:number[]=[]
let yarr:number[]=[]
const ipt:string="file"   // data from file or not
if(ipt==="file"){reader()}
else{
for(let i=0;i<35;i++){
    xarr[i]=Math.random()*10
    yarr[i]=Math.random()*10
    st=st+xarr[i]+"\t"+yarr[i]+"\n"
}
}
st=st+"end\n"
let points:point[]=[]
for (let i = 0; i < xarr.length; i++) {
    const el: point = {
        x: Number(xarr[i]),
        y: Number(yarr[i]), angle:0 ,
        discarded: false, zero:false
    };
    points.push(el)
}
var vsort = (a: point,b: point) => {
    if (b.y < a.y) return 1;
    if (b.y > a.y) return -1;
    else {
        if (b.x < a.x) return 1;
        if (b.x > a.x) return -1;
        return 0
    }
  };
  points.sort(vsort)
  console.log("point zero="+points[0])
      for(let i=0;i<xarr.length;i++){
         points[i].angle=arcos(Number(points[0].x),Number(points[i].x),Number(points[0].y),Number(points[i].y))
        }
    var byangle=(a:point,b:point)=>{
        if(b.angle<a.angle)return 1
        if(b.angle>a.angle)return -1
        else return 0
    }
    points.sort(byangle)
    points[0].zero=true
console.log(points[points.length-1])
let curr=0
let i=0     // safety
do {
    let c1=ccw(points[curr].x,points[curr+1].x,points[curr+2].x,points[curr].y,points[curr+1].y,points[curr+2].y)
    if(c1){curr++}
    else{console.log("removed"+points.splice(curr+1,1))   // remove point
        curr-=1
  }  
    i++;
  }
  while (i < 250 && curr<points.length-2);
  for(i=0;i<points.length;i++){
    console.log(points[i].x+"  "+points[i].y)
    st=st+points[i].x+"\t"+points[i].y+"\n"
  }
  syncWF('./example.txt',st)
// end of main
function arcos(x1: number, x2: number, y1: number, y2: number) {
  let x = x2 - x1
  let y = y2 - y1
      let res= Math.acos(x / Math.sqrt(x * x + y * y))
  if(isNaN(res))res=0
      return res}
function ccw(x1:number,x2:number,x3:number,y1:number,y2:number,y3:number ) // check if it is a left turn
{let bvar= (x2-x1)*(y3-y1)-(y2-y1)*(x3-x1)>0
return bvar
}
function reader(){
  let rv=syncread('./input.txt');
  let sarr=rv.split("\n")
  console.log("len="+sarr.length)
  let i:number
  for(i=0;i<sarr.length;i++){
    let ele=sarr[i].split("\t")
    let temp1=!isNaN(Number(ele[0]))
    let temp2=!isNaN(Number(ele[1]))
    if(temp1&&temp2){
      xarr[i]=Number(ele[0])
      yarr[i]=Number(ele[1])
      console.log(i+":  "+xarr[i]+"  "+yarr[i])
      st=st+xarr[i]+"\t"+yarr[i]+"\n"
    }
  }
}
  function syncWF(fname: string, data: any) {
    /**
     * flags:
     *  - w = Open file for reading and writing. File is created if not exists
     *  - a+ = Open file for reading and appending. The file is created if not exists
     */
    writeFileSync(join(__dirname, fname), data, {      flag: 'w',    });
      return 1;
  }  
  function syncread(filename: string) {
      const cont = readFileSync(join(__dirname, filename), 'utf-8');
      return cont;
  }
Author
Worf
Views
384
First release
Last update
Rating
0.00 star(s) 0 ratings

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