# Drawing a scatter best fit chart [Reference](http://wiki.pchart.net/doc.scatter.drawscatterbestfit.html) ```php require '/path/to/your/vendor/autoload.php'; use CpChart\Chart\Scatter; use CpChart\Data; use CpChart\Image; /* Create the Data object */ $data = new Data(); /* Create the X axis and the binded series */ for ($i = 0; $i <= 360; $i = $i + 10) { $data->addPoints(rand(1, 20) * 10 + rand(0, $i), "Probe 1"); } for ($i = 0; $i <= 360; $i = $i + 10) { $data->addPoints(rand(1, 2) * 10 + rand(0, $i), "Probe 2"); } $data->setAxisName(0, "X-Index"); $data->setAxisXY(0, AXIS_X); $data->setAxisPosition(0, AXIS_POSITION_TOP); /* Create the Y axis and the binded series */ for ($i = 0; $i <= 360; $i = $i + 10) { $data->addPoints($i, "Probe 3"); } $data->setSerieOnAxis("Probe 3", 1); $data->setAxisName(1, "Y-Index"); $data->setAxisXY(1, AXIS_Y); $data->setAxisPosition(1, AXIS_POSITION_LEFT); /* Create the 1st scatter chart binding */ $data->setScatterSerie("Probe 1", "Probe 3", 0); $data->setScatterSerieDescription(0, "This year"); $data->setScatterSerieColor(0, ["R" => 0, "G" => 0, "B" => 0]); /* Create the 2nd scatter chart binding */ $data->setScatterSerie("Probe 2", "Probe 3", 1); $data->setScatterSerieDescription(1, "Last Year"); /* Create the Image object */ $image = new Image(400, 400, $data); /* Draw the background */ $settings = ["R" => 170, "G" => 183, "B" => 87, "Dash" => 1, "DashR" => 190, "DashG" => 203, "DashB" => 107]; $image->drawFilledRectangle(0, 0, 400, 400, $settings); /* Overlay with a gradient */ $image->drawGradientArea(0, 0, 400, 400, DIRECTION_VERTICAL, [ "StartR" => 219, "StartG" => 231, "StartB" => 139, "EndR" => 1, "EndG" => 138, "EndB" => 68, "Alpha" => 50 ]); $image->drawGradientArea(0, 0, 400, 20, DIRECTION_VERTICAL, [ "StartR" => 0, "StartG" => 0, "StartB" => 0, "EndR" => 50, "EndG" => 50, "EndB" => 50, "Alpha" => 80 ]); /* Write the picture title */ $image->setFontProperties(["FontName" => "Silkscreen.ttf", "FontSize" => 6]); $image->drawText(10, 13, "drawScatterBestFit() - Linear regression", [ "R" => 255, "G" => 255, "B" => 255 ]); /* Add a border to the picture */ $image->drawRectangle(0, 0, 399, 399, ["R" => 0, "G" => 0, "B" => 0]); /* Set the default font */ $image->setFontProperties(["FontName" => "pf_arma_five.ttf", "FontSize" => 6]); /* Set the graph area */ $image->setGraphArea(50, 60, 350, 360); /* Create the Scatter chart object */ $myScatter = new Scatter($image, $data); /* Draw the scale */ $myScatter->drawScatterScale(); /* Turn on shadow computing */ $image->setShadow(true, ["X" => 1, "Y" => 1, "R" => 0, "G" => 0, "B" => 0, "Alpha" => 10]); /* Draw a scatter plot chart */ $myScatter->drawScatterPlotChart(); /* Draw the legend */ $myScatter->drawScatterLegend(280, 380, ["Mode" => LEGEND_HORIZONTAL, "Style" => LEGEND_NOBORDER]); /* Draw the line of best fit */ $myScatter->drawScatterBestFit(); /* Render the picture (choose the best way) */ $image->autoOutput("example.drawScatterBestFit.png"); ```