Mega Code Archive
Removeduplicates
<![CDATA[
Remove duplicates (from a stringlist,
although the algorithm can easily be
applied with other data structures).
Note however that IF you're not dealing
with an entity (like a string list) that
handles 'pushing all subsequent items
downward' (ie re-indexing) after an
item has been deleted, THEN you need
to code ways of dealing with that
yourself... (see second example)
Richard Ebbs Jan 2000
'Skeleton' code hacked from more a more
extensive function, and -NOT TESTED...
procedure RemoveDuplicates(inFileName: String);
var
counterOne: Integer;
counterTwo: Integer;
tempLines: TStringList;
inFile: TextFile;
tempStr: String;
duplicateFound: Boolean;
begin
tempLines := TStringList.Create;
if FileExists(infileName) then
begin
AssignFile(inFile, inFileName);
ReSet(inFile);
while not EOF(inFile)do
begin
ReadLn(inFile, tempStr);
tempLines.Append(tempStr);
end;
counterOne := 0;
while counterOne < tempLines.Count - 2 do
begin
counterTwo := counterOne + 1;
while counterTwo < tempLines.Count - 1 do
begin
duplicateFound := FALSE;
if (tempLines[counterOne] = tempLines[counterTwo]) then
begin
duplicateFound := TRUE;
tempLines.Delete(counterTwo);
end;
if not duplicateFound then Inc(counterTwo);
end;
Inc(counterOne);
end; {while}
ReWrite(inFile);
CloseFile(inFile);
tempLines.SaveToFile(inFileName);
end; {if}
tempLines.Free;
end;
here's another example, looking for and removing duplicate lines in a
(slightly compilicated) data structure to keep track of (drawing) lines.
See below the procedure for detial on the data structure.
procedure TWireFrame.RemoveDuplicateLines(var wFrameLines: TWFrameLines;
ptMatrix3D: TPtMatrix3D;
var linesNum: Integer);
var
lineIdx: Integer;
counterOne: Integer;
counterTwo: Integer;
counterThree: Integer;
duplicateFound: Boolean;
AEnd1X: Real;
AEnd1Y: Real;
AEnd1Z: Real;
AEnd2X: Real;
AEnd2Y: Real;
AEnd2Z: Real;
BEnd1X: Real;
BEnd1Y: Real;
BEnd1Z: Real;
BEnd2X: Real;
BEnd2Y: Real;
BEnd2Z: Real;
begin
counterOne := 0;
while counterOne < linesNum - 2 do
begin
counterTwo := counterOne + 1;
while counterTwo < linesNum - 1 do
begin
duplicateFound := FALSE;
AEnd1X := ptMatrix3D[wFrameLines[CounterOne].endPt1].x;
AEnd1Y := ptMatrix3D[wFrameLines[CounterOne].endPt1].y;
AEnd1Z := ptMatrix3D[wFrameLines[CounterOne].endPt1].z;
AEnd2X := ptMatrix3D[wFrameLines[CounterOne].endPt2].x;
AEnd2Y := ptMatrix3D[wFrameLines[CounterOne].endPt2].y;
AEnd2Z := ptMatrix3D[wFrameLines[CounterOne].endPt2].z;
BEnd1X := ptMatrix3D[wFrameLines[CounterTwo].endPt1].x;
BEnd1Y := ptMatrix3D[wFrameLines[CounterTwo].endPt1].y;
BEnd1Z := ptMatrix3D[wFrameLines[CounterTwo].endPt1].z;
BEnd2X := ptMatrix3D[wFrameLines[CounterTwo].endPt2].x;
BEnd2Y := ptMatrix3D[wFrameLines[CounterTwo].endPt2].y;
BEnd2Z := ptMatrix3D[wFrameLines[CounterTwo].endPt2].z;
if ((Floor(AEnd1X) = Floor(BEnd1X)) and
(Floor(AEnd1Y) = Floor(BEnd1Y)) and
(Floor(AEnd1Z) = Floor(BEnd1Z)) and
(Floor(AEnd2X) = Floor(BEnd2X)) and
(Floor(AEnd2Y) = Floor(BEnd2Y)) and
(Floor(AEnd2Z) = Floor(BEnd2Z))) then
begin
duplicateFound := TRUE;
//now effectively delete wFrameLines[CounterTwo]
//by effectively re-indexing the wFrameLines data
//structure such that all subsequent wFrameLines
//entries are shifted 'upwards'
for counterThree := (counterTwo + 1) to linesNum do
begin
wFrameLines[counterThree - 1] := wFrameLines[counterThree];
end;
Dec(linesNum);
end;
if not duplicateFound then Inc(counterTwo);
end;
Inc(counterOne);
end; {while}
end;
The 'ptMatrix3D' data structure holds POINTS data.
The 'wFrameLines' (ie wireFrame lines) data structure keeps track
of the LINES between the points. Each wFrameLines record in the
array has integer fields for 'endpoints' which are simply indexes
into the ptMatrix array.
To access a (coordinate) value from the point matrix relating to
a particular line, we would use syntax like this:
x := wireFrame.ptMatrix3D[wireFrame.wFrameLines[lineIdx].endPt1].x;
y := wireFrame.ptMatrix3D[wireFrame.wFrameLines[lineIdx].endPt1].y;
where x and y are both Real values.
Happy hunting.
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