python lambda函数语法错误

Question

def get_cluster_rows():
for path, rows in itertools.groupby(get_word_rows(), key=lambda x: x[0]):
    wordcounts = [(w,c) for _,w,c in rows]
    wordcounts.sort(key=lambda (w,c): -c)

    yield path, len(wordcounts), wordcounts[:50], wordcounts

语法错误:语法无效:

wordcounts.sort(key=lambda (w,c): -c)
                           ^

如何用 (w,c) 编写 lambda 函数？

Answer 1

你应该删除括号:

wordcounts.sort(key=lambda w, c: -c)