How do you check whether a request is from the admin panel?

I’m filtering some posts, and it’s working fine in the from end, but it’s also filtering the posts in the admin, which I don’t want.

Here is some example code of what I’m trying to do, and the ??? is where I’m stuck

add_filter('the_posts', 'my_function' , 1 );

function my_function( $posts ) {

    //
    // Check to see if we are logged into the admin panel
    //
    if (???) {
        return $posts;
    }

    //
    // If we are not in the admin, filter the posts
    //

    // create an array to hold the posts we want to show
    $new_posts = array();

    //
    // loop through all the post objects
    //
    foreach( $posts as $post ) {

        $include = true;

        //
        // Perform Filter comparison
        //
        if ($filterPost>=1) {
            $include = false;
        }

        //
        // if we want to include it then
        // add the post object to the new posts array
        //
        if ( $include === true ) {
            $new_posts[] = $post;
        }
    }

    //
    // send the new post array back to be used by WordPress
    //
	return $new_posts;
}