擅长:python、mysql、java
<pre><code>x = pd.DataFrame.from_items([('A', [1,1, 2, 3]), ('B', [4,3, 5, 6])])
def foo(B):
df = pd.DataFrame(np.random.randn(B,2), columns=['X','Y'])
df['tmp'] = B
return df
x.merge(pd.concat([foo(4), foo(3)]), left_on='B', right_on='tmp', how='left').drop('tmp',1)
</code></pre>