In this example we are going to draw a simple Bar graph. Take a school for exmaple. We are going to draw a graph for week days and the total number of student that come to school.

First of all we declare two arrays. The first for the student and the second for week days. Then we calculate the maximal number of student. On the basis of that number we are going to calculate the percentage length of the other bar graphs.

Code:
<html>
<meta http-equiv="Content-Language" content="en-us">
<title>Simple Bar Graph .. by viji patil</title>
<body>
<?php

\$data = array('100','200','300','400','500','350','270');
\$x_fld = array('Sun','Mon','Tue','Wen','Thu','Fir','Sat');
\$max = 0;
for (\$i=0;\$i<7;\$i++){
if (\$data[\$i] > \$max)\$max=\$data[\$i];  // find the largest data
}
\$im = imagecreate(320,255); // width , height px

\$white = imagecolorallocate(\$im,255,255,255); // allocate some color from RGB components remeber Physics
\$black = imagecolorallocate(\$im,0,0,0);   //
\$red = imagecolorallocate(\$im,255,0,0);   //
\$green = imagecolorallocate(\$im,0,255,0); //
\$blue = imagecolorallocate(\$im,0,0,255);  //
//
// create background box
//imagerectangle(\$im, 1, 1, 319, 239, \$black);
//draw X, Y Co-Ordinate
imageline(\$im, 10, 5, 10, 230, \$blue );
imageline(\$im, 10, 230, 300, 230, \$blue );
//Print X, Y
imagestring(\$im,3,15,5,"Students",\$black);
imagestring(\$im,3,280,240,"Days",\$black);
imagestring(\$im,5,100,50,"Simple Graph",\$red);
imagestring(\$im,5,125,75,"by Vijit",\$green);

// what next draw the bars
\$x = 15;    // bar x1 position
\$y = 230;    // bar \$y1 position
\$x_width = 20;  // width of bars
\$y_ht = 0; // height of bars, will be calculated later
// get into some meat now, cheese for vegetarians;
for (\$i=0;\$i<7;\$i++){
\$y_ht = (\$data[\$i]/\$max)* 100;    // no validation so check if \$max = 0 later;
imagerectangle(\$im,\$x,\$y,\$x+\$x_width,(\$y-\$y_ht),\$red);
imagestring( \$im,2,\$x-1,\$y+1,\$x_fld[\$i],\$black);
imagestring( \$im,2,\$x-1,\$y+10,\$data[\$i],\$black);
\$x += (\$x_width+20);   // 20 is diff between two bars;

}
imagejpeg( \$im, "graph.jpeg", 90);
imagedestroy(\$im);
echo "<img src='graph.jpeg'><p></p>";

?>
</body>
</html>