WORKING WITH VERY LARGE WORD LISTS

Dear Delphi Experts,

How I starting to do a program that involves comparing two very large word lists (~40.000 and 70.000 words) and finding out which words
are on one list and not on the other (and/or vice versa).

Each large word lists must be textfiles (.txt) and the results must be
presetend in a third textfile or listbox.

Many Thanks

LeTchev
letchevAsked:
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SmortexCommented:
Try this :
Load each word list in a TStringList (One word per line) avec sort them.

Create a function that search an item in a list.

Here is an example. In order to make it easier to read, I used 2 TListBox. When an item is clicked, a TLabel get the caption "True" if the item selected is found in the second TListBox, "False" if it was not found :

procedure TForm1.ListBox1Click(Sender: TObject);
  function FindTheOther(AWord: string; AList: TStringList): Boolean;
  var
    Offset, Step, CompResult: integer;
  begin
    Offset := AList.Count div 2;
    Step   := AList.Count;
    while Step <> 0 do
    begin
      Step := Step div 2;
      if Offset + Step >= AList.Count then
        Step := AList.Count - Offset - 1;
      CompResult := CompareText(AWord,AList[offset]);
      if CompResult = 0 then
      begin
        Result := True;
        Exit;
      end
      else
        if CompResult > 0 then
          Offset := Offset + Step
        else
          Offset := Offset - Step;
    end;
    Result := False;
  end;
begin
  Label1.Caption := BoolToStr(FindTheOther(ListBox1.Items[ListBox1.ItemIndex],TStringList(ListBox2.Items)),True);
end;

Hope that help :)

Regards
SmortexCommented:
Ooops....

This function should work better ;)

procedure TForm1.ListBox1Click(Sender: TObject);
  function FindTheOther(AWord: string; AList: TStringList): Boolean;
  var
    Offset, Step, CompResult: integer;
    LastChance : Integer;
  begin
    Offset := Ceil(AList.Count / 2);
    Step   := Ceil(AList.Count / 2);
    LastChance := 2;
    while LastChance <> 0 do
    begin

      Step := Ceil(Step / 2);

      if Step = 1 then
        Dec(LastChance);

      if Offset < 0 then
        Offset := 0;
      if Offset >= AList.Count then
        Offset := AList.Count - 1;

      CompResult := CompareText(AWord,AList[offset]);
      if CompResult = 0 then
      begin
        Result := True;
        Exit;
      end
      else
        if CompResult > 0 then
        begin
          Offset := Offset + Step;
        end
        else
        begin
          Offset := Offset - Step;
        end;
    end;
    Result := False;
  end;
begin
  Label1.Caption := BoolToStr(FindTheOther(ListBox1.Items[ListBox1.itemindex],TStringList(ListBox2.Items)),True);
end;

Sorry....

Regards

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letchevAuthor Commented:
Dear Smortex,

Sorry, but it is not I want. Firstly I would need a routine for reading wordlists from .txt or .csv files. for example

List1.LoadFromFile('c:\1.txt');
List2.LoadFromFile('c:\2.txt');

ListBox3.Items.Add (here the common words found in list1 and list2

it is possible?

Thank you for your patience.

Letchev
SmortexCommented:
Won can do this very easely using my function :

  List1 := TStringList.Create;
  List2 := TStringList.Create;
  try
    List1.LoadFromFile('c:\1.txt');
    List2.LoadFromFile('c:\2.txt');

    List1.Sort;
    List2.Sort;

    for i := 0 to Pred(List1.Count) do
      if FindTheOther(List1[i],List2) then
        ListBox1.Items.Add(List1[i]);

  finally
    List1.Free;
    List2.Free;
  end;

Regards
SmortexCommented:
Note that if you dont make any search (with my "FindTheOther" function) on the first list (List1) you do not have to sort it :)
This line can so be removed :
    List1.Sort;

Regards
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