#!/usr/bin/env python
# coding: utf-8

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import numpy as np
import pandas as pd


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df=pd.DataFrame(data=np.array([['A','A','B','B','B'],['yes','no','yes','no','yes'],[1,1,1,1,1]]).T,columns=['letter','yn','ones'])


# In[9]:


df


# In[11]:


df.loc[(df.letter=='A')&df.yn.str.contains('y')]


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