NameError:未定义全局名称"_"

Question

代码:

if (query_id, _) in hashtable[bucket]:

我希望这在for循环中工作,但它会给出这个错误:

NameError:未定义全局名称"_"

hastable[bucket]如果重要的是一对列表_(我怀疑).有任何想法吗？

Answer 1

The x in y is not magic; it's basically the same as y.__contains__(x). Therefore, in cannot search with placeholders; the left argument is fully evaluated. Instead, use

if any(query_id == qid for (qid, _) in hashtable[bucket]):