Aggregate posts from different categories on the front page

do you need something like this

$total_post_per_categories = 3; //
$cat_id_array = array(70,9,126); //use your own post

foreach ($cat_id_array as $cat_id) { 

	if ($exclude_all_this_post !="") {
		$exclude = "&exclude=" . $exclude_all_this_post; //exclude query syntax
	}

	$argument = "numberposts=$total_post_per_categories&category=$cat_id" . $exclude ."";
	$myposts_based_cat = get_posts($argument);  //all post with exlude post

	if (is_array($myposts_based_cat)) {
		$output .= $argument . "<br /><br />";
		foreach ($myposts_based_cat as $post) {

			if ($post === end($myposts_based_cat)) { //end of array
				$exclude_all_this_post .= $post->ID;
			} else {
				$exclude_all_this_post .= $post->ID . ",";
			}

			$output .=   $post->post_title;
			$output .=   "[$cat_id] ";
			$output .=  "[postid : " . $post->ID . "]";
			$output .= "<br />";
		}
	}
	$output .= "<br />";
}

echo "$output";

This is what I ended up doing. It seems to work. Not sure if it’s the best way or the right way but it appears to be working. Any feedback would be appreciated.

<div class="frontpage">
<h3>What's New</h3>
	<?php $the_query = new WP_Query('cat=6&showposts=4&orderby=post_date&order=desc');
	while ($the_query->have_posts()) : $the_query->the_post();
	$do_not_duplicate = $post->ID; ?>
	<div class="story">
		<?php the_excerpt('Read more...'); ?>
	</div>
	<?php endwhile; ?>

	<h3>Ask the Doc</h3>
	<?php $the_query = new WP_Query('cat=5&showposts=4&orderby=post_date&order=desc');
	while ($the_query->have_posts()) : $the_query->the_post();
	$do_not_duplicate = $post->ID; ?>
	<div class="story">
		<?php the_excerpt('Read more...'); ?>
	</div>
	<?php endwhile; ?>
</div>

Well, that worked fine for two loops but I forgot I needed a third. I tried your code above uwiuw but it kept spitting out other data besides the actual post content. Guess I still need some help with this.

i have test it and i think you code is more suitable for any loop. When you choose wp_query then you have ability to make a pagination. so it’s better. ??

Btw, is it possible to use $do_not_duplicate in the second WP_Query() arguments. so you can make it more bullet proof. so when there a post who has more then on category id (for example, 5 and 6 ) will not show on other looping.

it kept spitting out other data besides the actual post content

what do you mean ? i don’t understand ??
Btw, you can debug those $post array in my code use print_r and comment every not useful $output (I’m sorry for my grammatical)