循环中的list.append（）只能返回最终列表

Question

例如：

a = {}; 
b = [];
for i in range(20):
    b.append(i)
    a[i] = b

循环后，a的所有键都链接到相同的最终列表b [0,1,2,...,19]。 但是，我想要的是a[0] = [0]，a[1] = [0,1]，a[2] = [0,1,2]。 我不知道这是怎么了。

Answer 1

// Exclude products in recently viewed products widget from "machine" product category
add_filter( 'woocommerce_recently_viewed_products_widget_query_args', 'custom_recently_viewed_products_widget_query_args', 10, 1 );
function custom_recently_viewed_products_widget_query_args( $args ) {

    $args['tax_query'][] = array(
           'taxonomy' => 'product_cat',
           'field'    => 'slug',
           'terms'    => array( 'machine' ), 
           'operator' => 'NOT IN', 
    );

    return $args;
}

希望有帮助