title: Pandas: Round integers before joining dataframes
body: <p>I have two data frames that both contain coordinates. One of them, <code>df1</code>, has coordinates at a better resolution (with decimals), and I would like to join it to <code>df2</code> which has a less-good resolution:</p>
  <pre><code>import pandas as pd
  
  df1 = pd.DataFrame({'x': [1.1, 2.2, 3.3],
                      'y': [2.3, 3.3, 4.1],
                      'val': [10,11,12]})
  
  df2 = pd.DataFrame({'x': [1,2,3,5.5],
                      'y': [2,3,4,5.6]})
  
  df1['x_org']=df1['x']
  df1['y_org']=df1['y']
  df1[['x','y']] = df1[['x','y']].round()
  df1 = pd.merge(df1, df2, how='left', on=['x','y'])
  
  df1.drop({'x','y'}, axis=1)
  # rename...
  </code></pre>
  <p>The code above does exactly what I want, but it is a bit cumbersome. Is there an easier way to achieve this?</p>