title: How to perform inner join in multiple columns in pandas
body: <p>I have 2 dataframe namely accidents_data which has 15 columns and bad_air_quality_data dataframe whch has 5 columns.</p>
  
  <p>Now i'd like to inner join both data frames on column ['District Name', 'Weekday', 'Hour', 'Month'] and finally keep only the data from accidents_data after joining. </p>
  
  <p>accidents_data:</p>
  
  <p><a href="https://i.stack.imgur.com/Rt2N6.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Rt2N6.png" alt="accidents_data"></a></p>
  
  <p>bad_air_quality_data:</p>
  
  <p><a href="https://i.stack.imgur.com/1wL0A.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1wL0A.png" alt="bad_air_quality_data"></a></p>
  
  <p>I tried merging both the dataframes using the below line but it does not show any results.</p>
  
  <pre><code>accidents_data_bad_air = pd.merge(accidents_data, bad_air_quality_data, on=['District Name', 'Weekday', 'Month', 'Hour'], how='inner')
  </code></pre>