I have two VirtualStringTrees, first VST has been populated with data and I want to check the second VST and add nodes that are not already in the first VST. Or I want to add those nodes from second VST that are not duplicates of first VST.
procedure Tcreatevtform.copy2tosimvt(vt: Tvirtualstringtree);
var
data: PMyRec;
simvtdata: PMyRectF;
rootnode, simvtnode: PVirtualNode;
ty: string;
begin
rootnode := vt.GetFirst; //vt is second virtualstringtree
while Assigned(rootnode) do
begin
data := vt.GetNodeData(rootnode);
ty := data^.caption;
if checksimduplicate(ty)=false then
begin
simvtnode := similarvt.AddChild(nil); //similarvt is the first virtualstringtree
simvtdata := similarvt.GetNodeData(simvtnode);
simvtdata^.caption := data^.caption;
end;
rootnode := vt.GetNext(rootnode,false);
end;
end;
function Tcreatevtform.checksimduplicate(t: string): boolean;
var
data: PMyRectf;
rootnode: PVirtualNode;
typew: string;
begin
Result := False;
rootnode := similarvt.GetFirst;
while Assigned(rootnode) do
begin
data := similarvt.GetNodeData(rootnode);
typew := data^.caption; // problem here, typew is always a constant or it is always the first
if t=typew then
begin
// node's caption of vt (letter 'a' is the first node's caption in my
// app. So this function is always false.
Result := True;
Break;
end;
similarvt.GetNext(rootnode, False);
end;
end;
I am using D7.
Finding all items that are in one list but not a second can be done easily with a list comparison algorithm. Here's the basic idea:
Sort both lists
Take 2 index variables, one for each list, and start at the start of each list
Compare the two indexed items from each list according to the sort order.
If they're equal, then the same item is in both lists. Increment both indexes.
If the first item is less than the second one, then it's not in the second list. Increment the first index.
If the second item is less than the first one, then it's not in the first list. Increment the second index.
Repeat until you reach the end of one of the lists. All remaining items in the other list are not in the first list.
You can add actions to the equals case or either the first-unique or second-unique case to determine what to do in these cases. In your specific case, you'll want to make the second-unique case add an item to the VST. It might get more complicated if you have to preserve tree structure, but that's the basic idea.
Related
I have DevExpress cxGrid and I would like to get the Ids of the adjacent records. I can use them in the following use case: user deletes focused record and I position the (grid view) cursor on one of the adjacent records (as determined but the current sorting and grouping order of the grid view). Otherwise the position of the grid cursor is poorly determined after removal of the record and after refreshing the grid view.
I have made the following attempts but they are not working - the Id values are junk:
procedure GetAdjacentRecordIds(AView: TcxGridDBTableView; ACdFieldName: string; var APrevId, AId, ANextId: Integer);
var Item: TcxCustomGridTableItem;
RecIdx: Integer;
i, RecCount: Integer;
begin
APrevId:=-1;
AId:=-1;
ANextId:=-1;
if Trim(AIdFieldName)='' then Exit;
if not Assigned(AView) then Exit;
if not Assigned(AView.DataController) then Exit;
Item:=AView.DataController.GetItemByFieldName(UpperCase(AIdFieldName));
if not Assigned(Item) then Exit;
{//First attempt, didn't work, AId was the right one, but APrevId and ANextId were junk
RecIdx:=AView.DataController.FocusedRecordIndex;
AId:=AView.DataController.Values[RecIdx, Item.Index];
APrevId:=AView.DataController.Values[RecIdx-1, Item.Index];
ANextId:=AView.DataController.Values[RecIdx+1, Item.Index];}
//Second attempt, doesn't work, all three Ids are junk
RecIdx:=-1;
RecCount:=AView.ViewData.RecordCount;
for i:=0 to RecCount-1 do begin
if AView.ViewData.Records[i].Focused then begin
RecIdx:=1;
Break;
end;
end;
if RecIdx<0 then Exit;
AId:=AView.ViewData.Records[RecIdx].Values[Item.Index];
if RecIdx>0 then
APrevId:=AView.ViewData.Records[RecIdx-1].Values[Item.Index];
if RecIdx<RecCount then
ANextId:=AView.ViewData.Records[RecIdx+1].Values[Item.Index];
end;
How can I correct this code to get the field values for adjacent records. Or maybe I should use Grid navigator and do prev/next on it, but I would like to find the values in invisible. And DataSet.DisableControls may stop the Grid navigator?
I used the DevExpress knowledgebase to find this answer. You are referencing the internal storage of the grid incorrectly. You can also use dataset.previous and dataset.next to position the record pointer in a bound grid, and simply use dataset.fieldbyname(AidFieldName).AsInteger to retrieve key values.
get-cell-value-by-column-name
procedure TForm1.Button1Click(Sender: TObject);
var
AColumn: TcxGridDBColumn;
I: Integer;
AView: TcxGridDBTableView;
v: Variant;
begin
AView := cxGrid1DBTableView1;
AColumn := TcxGridDBColumn( AView.FindItemByName('cxGrid1DBTableView1Capital'));
if Assigned(AColumn) then
for I := 0 to AView.ViewData.RowCount - 1 do
v := AView.DataController.Values[AView.ViewData.Rows[0].RecordIndex, AColumn.Index];
end;
Use of the navigation functions of DataSet is not the solution, because CxGrid can have completely different sorting order. But DataController navigation is good solution and there is no visual flickering as well. So, the solution is:
RecIdx:=AView.DataController.FocusedRecordIndex;
AId:=AView.DataController.Values[RecIdx, Item.Index];
if not AView.DataController.IsBOF then begin
AView.DataController.GotoPrev;
RecIdx:=AView.DataController.FocusedRecordIndex;
APrevId:=AView.DataController.Values[RecIdx, Item.Index];
AView.DataController.GotoNext;
end;
if not AView.DataController.IsEOF then begin
AView.DataController.GotoNext;
RecIdx:=AView.DataController.FocusedRecordIndex;
ANextId:=AView.DataController.Values[RecIdx, Item.Index];
AView.DataController.GotoPrev;
end;
It's easy to check that node is visible. But I don't know how to rightly define that node is presented on screen. I can find out only so:
BottomNode := Tree.BottomNode;
Node := Tree.TopNode;
IdBottomNode := Tree.AbsoluteIndex(BottomNode);
while Tree.AbsoluteIndex(Node) <> IdBottomNode do
begin
Node := Node.NextSibling;
if not Assigned(Node) then
Break;
end;
(code without checking)
But I think it is rather rough way. May be is there more accurate way?
You may write a function like follows. The Tree parameter there specifies the virtual tree, the Node is the node for which you want to check if it's visible, and the Column optional parameter is the index of a column if you would need to determine whether the node and even column is visible in client rect:
function IsNodeVisibleInClientRect(Tree: TBaseVirtualTree; Node: PVirtualNode;
Column: TColumnIndex = NoColumn): Boolean;
begin
Result := Tree.IsVisible[Node] and
Tree.GetDisplayRect(Node, Column, False).IntersectsWith(Tree.ClientRect);
end;
But maybe there's a more straightforward way...
I want the selected List Data to populate the tree
Here was my attempt towards it
if ListView1.Items[Count].Selected then
begin
Root := ListView1.Items[Count].Caption;
for Itr := TreeView1.Items.Count-1 downto 0 do Begin
if TreeView1.items[itr].Parent.Text = Root then begin
TreeNode := TreeView1.Items[itr].getFirstChild;
Treeview1.Items.AddChild(Treenode,ListView1.Items[Count].SubItems[0]);
break;
end;
end;
end;
But its creating new node and there is an index error.
Kindly help
You haven't provided any details about what your ListView data looks like, or what the TreeView is supposed to look like in relation to that data. But I suspect your code should probably look more like this instead:
if ListView1.Items[Count].Selected then
begin
Root := ListView1.Items[Count].Caption;
for Itr := TreeView1.Items.Count-1 downto 0 do begin
TreeNode := TreeView1.Items[itr];
if TreeNode.Text = Root then begin
TreeView1.Items.AddChild(TreeNode, ListView1.Items[Count].SubItems[0]);
break;
end;
end;
end;
Note that iterating through a TreeView backwards is VERY inefficient. Trees are not inherently indexable, so every time you access a node by index via the TreeView1.Items[] property, it has to start with the first node in the tree and iterate forwards counting nodes until it reaches the specified index. You are repeating that same forward scan for every node you access while going backwards. That is a lot of wasted overhead.
I have a cxGrid where I apply a filter to select certain records. When that is done I want to be able to update a field/column in the grid to mark each record that is to be used for the next operation.
I haven't been able to figure this out
Maybe I haven't been specific enough when describing my problem.
I have the cxGrid where I have applied a filter selecting some records.
What I then need to do is to click a columnheader and then have a field called fldselected set to True for these records.
What your updated q is asking for is straightforward and as usual with Devex stuff, it's
all in the OLH as long as you can find your way into it.
A way to find which rows currently match the filter is to use the
cxGrid1DBTableView1.DataController.FilteredRecordIndex[]
property. You can then find that record in the dataset to process it in some way using
cxGrid1DBTableView1.DataController.LocateByKey().
Update: The original version of this answer assumed that the dataset had an integer ID field.
As the OP has said he uses GUIDs instead, I've upddated it accordingly.
Assuming the TClientDataSet CDS1 has fields Guid : TGuidField, Name : TStringfield, size 32
and Selected : TBooleanField and is connected to
a cxDBTableView, with filtering enabled, of a TcxGrid.
Make sure the cxGrid1DBTableView1.DataController.KeyFieldNames is set to 'Guid'.
Add a regular TDBGrid to the form and point it at the same datasource as the TcxGrid. The point
of this is to make it easy to verify that the code is working as required.
Add the code below to the unit, and point cxDBTableView1's OnColumnHeaderClick at
the handler cxGrid1DBTableView1ColumnHeaderClick, and the form's OnCreate at the FormCreate.
Compiler & run
Code:
procedure TForm1.cxGrid1DBTableView1ColumnHeaderClick(Sender: TcxGridTableView;
AColumn: TcxGridColumn);
begin
if AColumn = cxGrid1DBTableView1Name then
ProcessFilteredRecords;
end;
procedure TForm1.FormCreate(Sender: TObject);
var
AGuid : TGuid;
i : Integer;
lResult : Longint;
begin
CDS1.IndexFieldNames := 'Name';
CDS1.CreateDataSet;
for i:= 0 to 6 do begin
lResult := SysUtils.CreateGUID(AGuid);
CDS1.Insert;
CDS1.FieldByName('Name').AsString := Chr(Ord('A') + i);
CDS1.FieldByName('Guid').AsString := GuidToString(AGuid);
CDS1.FieldByName('Selected').AsBoolean := False;
CDS1.Post;
end;
CDS1.First;
end;
procedure TForm1.ProcessFilteredRecords;
var
V : Variant;
i,
Index: Integer;
BM : TBookMark;
begin
BM := CDS1.GetBookMark;
CDS1.DisableControls;
try
for i := 0 to cxGrid1DBTableView1.DataController.FilteredRecordCount - 1 do begin
Index := cxGrid1DBTableView1.DataController.FilteredRecordIndex[i];
// Next, get the GUID value of the row
V := cxGrid1DBTableView1.DataController.Values[Index, 0];
if cxGrid1DBTableView1.DataController.LocateByKey(V) then begin
CDS1.Edit;
CDS1.FieldByName('Selected').AsBoolean := True;
CDS1.Post;
end;
end;
finally
CDS1.EnableControls;
CDS1.GotoBookmark(BM);
CDS1.FreeBookmark(BM);
end;
end;
Check out https://www.devexpress.com/Support/Center/Question/Details/A1095, the article from Dev Express. Don't let the fact that the article is 11 years old fool you. The same technique still applies. And you can set this up either in code or in the grid editor.
Create the column in the grid editor.
Set the columns DataBinding.ValueType to Boolean (if that's what you want the checkbox to represent)
Set the Data Controller's KeyFieldNames property. Very important! I have spent hours scratching my head with an non-functioning unbound column only to find that the KeyFieldNames wasn't set.
An unbound column can be referenced in your next operation using the DataController Records or Values array, depending on how you set that up. Because it is unbound you cannot reference it through the underlying DataSet though.
what is the fastest way to find duplicates in a Tstringlist. I get the data I need to search for duplicates in a Stringlist. My current idea goes like this :
var TestStringList, DataStringList : TstringList;
for i := 0 to DataStringList.Items-1 do
begin
if TestStringList.Indexof(DataStringList[i])< 0 < 0 then
begin
TestStringList.Add(DataStringList[i])
end
else
begin
memo1.ines.add('duplicate item found');
end;
end;
....
Just for completeness, (and because your code doesn't actually use the duplicate, but just indicates one has been found): Delphi's TStringList has the built-in ability to deal with duplicate entries, in it's Duplicates property. Setting it to dupIgnore will simply discard any duplicates you attempt to add. Note that the destination list has to be sorted, or Duplicates has no effect.
TestStringList.Sorted := True;
TestStringList.Duplicates := dupIgnore;
for i := 0 to DataStringList.Items-1 do
TestStringList.Add(DataStringList[i]);
Memo1.Lines.Add(Format('%d duplicates discarded',
[DataStringList.Count - TestStringList.Count]));
A quick test shows that the entire loop can be removed if you use Sorted and Duplicates:
TestStringList.Sorted := True;
TestStringList.Duplicates := dupIgnore;
TestStringList.AddStrings(DataStringList);
Memo1.Lines.Add(Format('%d duplicates discarded',
[DataStringList.Count - TestStringList.Count]));
See the TStringList.Duplicates documentation for more info.
I think that you are looking for duplicates. If so then you do the following:
Case 1: The string list is ordered
In this scenario, duplicates must appear at adjacent indices. In which case you simply loop from 1 to Count-1 and check whether or not the elements of index i is the same as that at index i-1.
Case 2: The string list is not ordered
In this scenario we need a double for loop. It looks like this:
for i := 0 to List.Count-1 do
for j := i+1 to List.Count-1 do
if List[i]=List[j] then
// duplicate found
There are performance considerations. If the list is ordered the search is O(N). If the list is not ordered the search is O(N2). Clearly the former is preferable. Since a list can be sorted with complexity O(N log N), if performance becomes a factor then it will be advantageous to sort the list before searching for duplicates.
Judging by the use of IndexOf you use an unsorted list. The scaling factor of your algorithm then is n^2. That is slow. You can optimize it as David shown by limiting search area in the internal search and then the average factor would be n^2/2 - but that still scales badly.
Note: scaling factor here makes sense for limited workloads, say dozen or hundreds of strings per list. For larger sets of data asymptotic analysis O(...) measure would suit better. However finding O-measures for QuickSort and for hash-lists is a trivial task.
Option 1: Sort the list. Using quick-sort it would have scaling factor n + n*log(n) or O(n*log(n)) for large loads.
Set Duplicates to accept
Set Sorted to True
Iterate the sorted list and check if the next string exists and is the same
http://docwiki.embarcadero.com/Libraries/XE3/en/System.Classes.TStringList.Duplicates
http://docwiki.embarcadero.com/Libraries/XE3/en/System.Classes.TStringList.Sorted
Option 2: use hashed list helper. In modern Delphi that would be TDictionary<String,Boolean>, in older Delphi there is a class used by TMemIniFile
You iterate your stringlist and then check if the string was already added into the helper collection.
The scaling factor would be a constant for small data chunks and O(1) for large ones - see http://docwiki.embarcadero.com/Libraries/XE2/en/System.Generics.Collections.TDictionary.ContainsKey
If it was not - you add it with "false" value.
If it was - you switch the value to "true"
For older Delphi you can use THashedStringList in a similar pattern (thanks #FreeConsulting)
http://docs.embarcadero.com/products/rad_studio/delphiAndcpp2009/HelpUpdate2/EN/html/delphivclwin32/IniFiles_THashedStringList_IndexOf.html
Unfortunately it is unclear what you want to do with the duplicates. Your else clause suggests you just want to know whether there is one (or more) duplicate(s). Although that could be the end goal, I assume you want more.
Extracting duplicates
The previously given answers delete or count the duplicate items. Here an answer for keeping them.
procedure ExtractDuplicates1(List1, List2: TStringList; Dupes: TStrings);
var
Both: TStringList;
I: Integer;
begin
Both := TStringList.Create;
try
Both.Sorted := True;
Both.Duplicates := dupAccept;
Both.AddStrings(List1);
Both.AddStrings(List2);
for I := 0 to Both.Count - 2 do
if (Both[I] = Both[I + 1]) then
if (Dupes.Count = 0) or (Dupes[Dupes.Count - 1] <> Both[I]) then
Dupes.Add(Both[I]);
finally
Both.Free;
end;
end;
Performance
The following alternatives are tried in order to compare performance of the above routine.
procedure ExtractDuplicates2(List1, List2: TStringList; Dupes: TStrings);
var
Both: TStringList;
I: Integer;
begin
Both := TStringList.Create;
try
Both.AddStrings(List1);
Both.AddStrings(List2);
Both.Sort;
for I := 0 to Both.Count - 2 do
if (Both[I] = Both[I + 1]) then
if (Dupes.Count = 0) or (Dupes[Dupes.Count - 1] <> Both[I]) then
Dupes.Add(Both[I]);
finally
Both.Free;
end;
end;
procedure ExtractDuplicates3(List1, List2, Dupes: TStringList);
var
I: Integer;
begin
Dupes.Sorted := True;
Dupes.Duplicates := dupAccept;
Dupes.AddStrings(List1);
Dupes.AddStrings(List2);
for I := Dupes.Count - 1 downto 1 do
if (Dupes[I] <> Dupes[I - 1]) or (I > 1) and (Dupes[I] = Dupes[I - 2]) then
Dupes.Delete(I);
if (Dupes.Count > 1) and (Dupes[0] <> Dupes[1]) then
Dupes.Delete(0);
while (Dupes.Count > 1) and (Dupes[0] = Dupes[1]) do
Dupes.Delete(0);
end;
Although ExtractDuplicates3 marginally performs better, I prefer ExtractDuplicates1 because it reeds better and the TStrings parameter provides more usability. ExtractDuplicates2 performs noticeable worst, which demonstrates that sorting all items afterwards in a single run takes more time then continuously sorting every single item added.
Note
This answer is part of this recent answer for which I was about to ask the same question: "how to keep duplicates?". I didn't, but if anyone knows or finds a better solution, please comment, add or update this answer.
This is an old thread but I thought this solution may be useful.
An option is to pump the values from one stringlist to another one with the setting of TestStringList.Duplicates := dupError; and then trap the exception.
var TestStringList, DataStringList : TstringList;
TestStringList.Sorted := True;
TestStringList.Duplicates := dupError;
for i := 0 to DataStringList.Items-1 do
begin
try
TestStringList.Add(DataStringList[i])
except
on E : EStringListError do begin
memo1.Lines.Add('duplicate item found');
end;
end;
end;
....
Just note that the trapping of the exception also masks the following errors:
There is not enough memory to expand the list, the list tried to grow beyond its maximal capacity, a non-existent element of the list was referenced. (i.e. the list index was out of bounds).
function TestDuplicates(const dataStrList: TStringList): integer;
begin
with TStringlist.create do begin
{Duplicates:= dupIgnore;}
for it:= 0 to DataStrList.count-1 do begin
if IndexOf(DataStrList[it])< 0 then
Add(DataStrList[it])
else
inc(result)
end;
Free;
end;
end;