title: Add data from JSON in existing Pandas dataframe
body: <p>I'm trying to add a new row at the top of my existing dataframe (df_PRED). Data are coming from a json. The keys of the json (df_NEW) have exactly the same naming like the columns in the existing dataframe.</p>
  
  <pre><code>df_NEW = pd.read_json(dataJSON, lines=True) 
  df_PRED[-1] = df_NEW
  </code></pre>
  
  <p>Error: <em>Wrong number of items passed 36, placement implies 1</em></p>
  
  <p>What's going wrong? Thank you for your hints.</p>