WP Upload Sort By File Type

<?php
/**
 * Plugin Name: Upload Sieve
 * Plugin URI: http://a2.gs
  * Description: Place Uploaded Files in directory by type rather than yr/mo.
 * Author: Your Name
 * Author URI: http://a2.gs
 * Version: 0.1.0
 */

/**
 * Set custom upload directory
 *
 * Images => /img
 * PDF    => /pdf
 * Misc   => /misc
 *
 * Note: Doesn't work with 'browser uploader'-files will end up in the desirted location with a broken reference in the media library
 * Note: Use with 'wp_update_attachment_metadata' hook if we want to define our own attachment metadata
 * Allowed file types: http://codex.wordpress.org/Uploading_Files#About_Uploading_Files_on_Dashboard
 */
function prefix_custom_upload_directory( $upload ) {

    $file_type = array();

    // Get file type
    if( ! empty( $_POST['name'] ) ) :

        $custom_directory = '';

        $file_type = wp_check_filetype( $_POST['name'] );
        $file_ext  = ( $file_type['ext'] ) ? $file_type['ext'] : '';

        // set directory based on file type
        if( in_array( strtolower( $file_ext ), array( 'jpg', 'jpeg', 'png', 'gif' ) ) ) :

            // Images
            $custom_directory = '/img';

        elseif( 'pdf' === strtolower( $file_ext ) ) :

            // PDF
            $custom_directory = '/pdf';

        else:

            // Misc
            $custom_directory = '/misc';

        endif;

        // update directory
        if( $custom_directory ) :

            // remove default subdir (year/month)
            $upload['path']    = str_replace( $upload['subdir'], '', $upload['path'] );
            $upload['url']     = str_replace( $upload['subdir'], '', $upload['url'] );

            // update paths
            $upload['subdir']  = $custom_directory;
            $upload['path']   .= $custom_directory;
            $upload['url']    .= $custom_directory;

        endif;

    endif;

    return $upload;

}
add_filter( 'wp_handle_upload_prefilter', 'prefix_pre_upload', 0 );
add_filter( 'wp_handle_upload', 'prefix_post_upload', 0 );





/**
 * Add custom directory filter
 *
 * 'prefix_custom_upload_directory'
 */
function prefix_pre_upload( $file ) {

    add_filter( 'upload_dir', 'prefix_custom_upload_directory' );
    return $file;
}

/* Place custom code above this line. */
?>