'get the active themes
theGThemes = av.GetActiveDoc.GetActiveThemes
theGrids = List.Make

'make the output filename
fnStats = av.GetProject.MakeFileName("Stats","STA")
fnStats = FileDialog.Put(fnStats,"*.STA","Input Statistics Filename")
if (fnStats = nil) then
  exit
end

'make sure all active themes are grid themes.
for each t in theGthemes
  if (t.Is(Gtheme).Not) then
    msgBox.Error(t.GetName + " Is not a Grid Theme cannot use it.","")
  else
    theGrids.Add(t)
  end
end

if (theGrids.Count < 2) then
  msgBox.Error("You need at least two active grid themes that are the same spatially.","Not enough GThemes")
  exit
end

'set up cell size and get rows and columns
GRID.SetAnalysisCellSize (#GRID_ENVTYPE_MAXOF , nil)
cols = theGrids.Get(0).GetGrid.GetNumRowsAndCols.Get(1)
rows = theGrids.Get(0).GetGrid.GetNumRowsAndCols.Get(0)

'how many total cells
elements = cols * rows

'set up an empty covarance and correlation matirx
'of the correct size
corMat = {}
for each i in 0..(theGrids.Count - 1)
  tmpLst = {}
  for each j in 0..(theGrids.Count - 1)
    tmpLst.Add("")
  end
  corMat.Add(tmpLst)
end

  
'fill out the matrix with correct values
cnt = 1
for each i in 0..(theGrids.Count - 1)
  for each j in i..(theGrids.Count - 1)
    g1 = theGrids.Get(i).GetGrid
    g1Stats = g1.GetStatistics
    g1Sum = g1Stats.Get(2) * elements
    
    g2 = theGrids.Get(j).GetGrid
    g2Stats = g2.GetStatistics
    g2Sum = g2Stats.Get(2) * elements
    
    sumProd = (g1Sum * g2Sum) / elements
    
    g3 = g1 * g2
    g3Stats = g3.GetStatistics
    
    g3Sum = g3Stats.Get(2) * elements
    
    SP = g3Sum - sumProd
    cov = SP/elements
    
    r = cov/(g1Stats.Get(3) * g2Stats.Get(3))
    
    lstTmp = {}
    lstTmp = corMat.Get(i)
    lstTmp.Set(j,r)
    corMat.Set(i,lstTmp)
    
    g1 = nil
    g2 = nil
  end
  cnt = cnt + 1
  av.PurgeObjects
end
av.PurgeObjects

for each i in 0..(corMat.Count-2)
  tmp1 = corMat.Get(i)
  for each j in (i+1)..(corMat.Count - 1)
    tmp2 = corMat.Get(j)
    tmp2.Set(i,tmp1.Get(j))
    corMat.Set(j,tmp2)
  end
end

maxCnt = 0
for each i in theGrids
  if (i.GetName.Count > maxCnt) then
    maxCnt = i.GetName.Count
  end
end

'create the output file
fileStat = LineFile.Make(fnStats,#FILE_PERM_WRITE)

'creat a buffer for spacing in the file
if (maxCnt > 10) then
  buf= String.MakeBuffer(maxCnt)
else
  buf = String.MakeBuffer(10)
end

cnt = 0
outLine = ""

fileStat.WriteElt("")
fileStat.WriteElt("Correlation Matrix")

cnt = 1
outLine = buf
for each g in theGrids
  outLine = outLine + g.GetName + String.MakeBuffer(15 - g.GetName.Count)
  cnt = cnt + 1
end
fileStat.WriteElt(outLine)

cnt = 0
outLine = ""
for each alst in corMat
  outLine = theGrids.Get(cnt).GetName + String.MakeBuffer(buf.Count - theGrids.Get(cnt).GetName.Count)
  for each x in alst
    outLine = outLine + x.asString + String.MakeBuffer(15 - x.asString.Count)
  end
  cnt = cnt + 1
  fileStat.WriteElt(outLine)
end

'close the file
fileStat.Close