Data-exploration script
The data-exploration tool consists of a single script (explore.php) that calls methods from the SimpleLinearRegressionHTML class and the JpGraph libary.
The script uses a simple processing logic. The first part of the
script performs basic validation on submitted form data. If the form
data validates, then the second part of the script is executed.
The second part of the script contains code for analyzing the data
and displaying summary results in HTML and graphics formats. The
essential structure of the explore.php script is shown in Listing 4:
Listing 4. The structure of explore.php
<?php
// explore.php
if (!empty($x_values)) {
$X = explode(",", $x_values);
$numX = count($X);
}
if (!empty($y_values)) {
$Y = explode(",", $y_values);
$numY = count($Y);
}
// display entry data entry form if variables not set
if ( (empty($title)) OR (empty($x_name)) OR (empty($x_values)) OR
(empty($y_name)) OR (empty($conf_int)) OR (empty($y_values)) OR
($numX != $numY) ) {
// Omitted code for displaying entry form
} else {
include_once "slr/SimpleLinearRegressionHTML.php";
$slr = new SimpleLinearRegressionHTML($X, $Y, $conf_int);
echo "<h2>$title</h2>";
$slr->showTableSummary($x_name, $y_name);
echo "<br><br>";
$slr->showAnalysisOfVariance();
echo "<br><br>";
$slr->showParameterEstimates($x_name, $y_name);
echo "<br>";
$slr->showFormula($x_name, $y_name);
echo "<br><br>";
$slr->showRValues($x_name, $y_name);
echo "<br>";
include ("jpgraph/jpgraph.php");
include ("jpgraph/jpgraph_scatter.php");
include ("jpgraph/jpgraph_line.php");
// The code for displaying the graphics is inline in the
// explore.php script. The code for these two line plots
// finishes off the script:
// Omitted code for displaying scatter plus line plot
// Omitted code for displaying residuals plot
}
?>
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