'DataThin.bas reads the data file and writes every nth point to a new file. Sub Main Debug.Print "----- ";Time;" -----" file1 = GetFilePath(,"dat;txt;xyz",,"Open Data File") n = InputBox("Read every n-th data point","Enter 'n'","2") file2 = Left(file1,Len(file1)-4)+"_Thinned_"+n+".dat" Open file1 For Input As #1 Open file2 For Output As #2 linenum = 0 While Not EOF(1) For i = 1 To n Line Input #1,a Next i Print #2,a Wend Debug.Print file2+" has been created." MsgBox(file2+" has been created.") End Sub