Exclude duplicated posts from wordpress custom queries - wordpress

Question

I'm building a template for a homepage which shows 4 latest posts on top and some groups of posts divided by category around the page (I'm using get_posts to perform queries).
What I'd like to do is exclude from these category posts any post already present in the latest four news on top.
I guess I should get that four post IDs and use the 'post__not_in' parameter in the "category" queries, but I can't make it work.
Dou you have any hints?
This is the code:
// First query: I get last four posts
$args = array(
'post_type' => 'post',
'post_status' => 'publish',
'numberposts' => 4
);
// In my dreams, this should be the array of post IDs
$ids->query_vars['page_id'];
// Second query: I get 5 posts for a given categoory and exclude posts with IDs from first query
$query = new WP_Query($args);
$args2 = array(
'numberposts' => 5,
'category' => 15,
'orderby' => 'post_date',
'order' => 'DESC',
'post__not_in' => $ids
);
$query2 = new WP_Query($args2);
$primaposizione = get_posts( $args2 );
foreach ( $primaposizione as $post ) : setup_postdata( $post );
... do the stuff ...
endforeach;
wp_reset_postdata();
UPDATE
<?php
$args = array(
'post_type' => 'post',
'post_status' => 'publish',
'orderby' => 'post_date',
'order' => 'DESC',
'posts_per_page' => 4
);
$query = new WP_Query($args);
$excludeID = array();
while ( $query->have_posts() ) : $query->the_post();
$excludeID = $post->ID;
endwhile;
$args = array(
'posts_per_page' => 1,
'orderby' => 'post_date',
'order' => 'DESC',
'category' => 15,
'post_type' => 'post',
'post_status' => 'publish',
'post__not_in' => array($excludeID)
);
$primaposizione = get_posts( $args );
foreach ( $primaposizione as $post ) : setup_postdata( $post );
$category = get_the_category();
$slug = $category[0]->category_nicename ;
$esteso = $category[0]->cat_name;
if(has_post_thumbnail()) { ?>
<span class="hidden-xs"><?php the_post_thumbnail('bones-thumb-300', array('class' => 'img-responsive')) ?></span>
<?php } ?>
<h3 class="ellipsis"><?php the_title(); ?></h3>
<?php the_excerpt();?>
<?php endforeach;
wp_reset_postdata();
?>

Answer 1

The way you're trying to select the ID's is not going to work. You have to call wp_query first. I think this should work:
$args = array(
'post_type' => 'post',
'post_status' => 'publish',
'numberposts' => 4
);
$query = new WP_Query($args);
$excludeID = array();
while ( $query->have_posts() ) : $query->the_post(); ?>
$excludeID[] = $post->ID; // forgot the brackets
// do stuff
endwhile;
(...)