setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
die("Connection failed: " . $e->getMessage());
}
// Fetch data
$Data = [];
$stmt = $conn->query("SELECT * FROM temp ORDER BY ID;");
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
$Data[] = $row;
}
// Close DB connection
$conn = null;
// Extract columns
$labels = array_column($Data, 'Date');
$temps = array_column($Data, 'Temp');
// Convert dates to numeric values (e.g. index) for regression
$x_vals = range(0, count($temps) - 1);
$y_vals = $temps;
// Linear regression calculation (y = a * x + b)
$n = count($x_vals);
$sum_x = array_sum($x_vals);
$sum_y = array_sum($y_vals);
$sum_xy = array_sum(array_map(fn($x, $y) => $x * $y, $x_vals, $y_vals));
$sum_x2 = array_sum(array_map(fn($x) => $x * $x, $x_vals));
$slope = ($n * $sum_xy - $sum_x * $sum_y) / ($n * $sum_x2 - $sum_x ** 2);
$intercept = ($sum_y - $slope * $sum_x) / $n;
// Generate trend line data
$trendLine = array_map(fn($x) => round($slope * $x + $intercept, 2), $x_vals);
?>
Temperature Chart with Trend Line
Temperature Trend: Poland Average