Load data points from external text file to chart

Load data points from external text file to chart

TextFile type is a file a sequence of elements of the same type. Standard I/O routines use the redefined TextFile or Text type, which represents a file containing characters organized into lines. AssignFile method Associates the name of an external file with a file variable. Reset opens an existing file. EOF tests whether the file position is at the end of a file. ReadLN reads a line of text from a file. CloseFile closes the open file.

Select following procedure in Browse button. It will show file selection dialog box and put selected file details in Edit1.Text

procedure TForm1.Button2Click(Sender: TObject);
begin
     { OpenDialog displays a file-selection dialog.
     FileName - Indicates the name and directory path of
     the last file selected. }
     If OpenDialog1.Execute Then
          Edit1.Text := OpenDialog1.FileName;
end;

This one reads external text data file and put the data in chart series.

procedure TForm1.Button1Click(Sender: TObject);
Var
    { A file a sequence of elements of the same type.
    Standard I/O routines use the predefined TextFile or
    Text type, which represents a file containing characters
    organized into lines. }
    Data : TextFile;

    X, Y : Real;
begin
    { This method deletes all Series values.
    Dependent Series are notified. If no new points are
    appended to the Series, nothing will be painted. }
    Chart1.Series[0].Clear;

    { Associates the name of an external file with a file variable. }
    AssignFile(Data, Edit1.Text);

    { Opens an existing file. }
    Reset(Data);

    { EOF - Tests whether the file position is at the end of a file. }
    While Not Eof(Data) Do
    Begin
        { Reads a line of text from a file. }
        Readln(Data, X, Y);

        Chart1.Series[0].AddXY(X, Y, '', clTeeColor);
    End;

    { Closes a file. }
    CloseFile(Data);
end;

Download This Delphi Tutorials.

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Load-data-points-external-file-chart.zip
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paparazzi :: May 01-2009 :: 08:27 PM

I'm glad to see that HERE everybody can download this Delphi Tutorial, and thank you for putting this up on the net 

Chris :: June 10-2009 :: 06:41 PM

Thank you for the good intro tutorial to Charts.
In my current application I am going to implement a chart for the first time.
I will use your examples as the guide.
Cheers...

Giovanni :: March 21-2011 :: 02:01 PM

Thanks for your fine tutorials. Clear, concise, effective. Congratulations !

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