title: Trying to Merge or Concat two pyspark.sql.dataframe.DataFrame in Databricks Environment
body: <p>I have two dataframes in Azure Databricks.  Both are of type: pyspark.sql.dataframe.DataFrame</p>
  
  <p>The number of rows are the same; indexes are the same.  I thought one of these code snippets, below, would do the job.</p>
  
  <p>First Attempt:</p>
  
  <pre><code>result = pd.concat([df1, df2], axis=1)
  
  
  Error Message: TypeError: cannot concatenate object of type "&lt;class 'pyspark.sql.dataframe.DataFrame'&gt;"; only pd.Series, pd.DataFrame, and pd.Panel (deprecated) objs are valid
  </code></pre>
  
  <p>Second Attempt:</p>
  
  <pre><code>result = pd.merge(df1, df2, left_index=True, right_index=True)
  
  Error Message:  TypeError: Can only merge Series or DataFrame objects, a &lt;class 'pyspark.sql.dataframe.DataFrame'&gt; was passed
  </code></pre>