title: Pandas Dataframe - Set Rows Equal to Other Rows
body: <p>For this basic dataframe, I'd like to set rows equal to other rows.  I have no trouble doing this one row at a time:</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  
  df = pd.DataFrame(np.random.randn(10, 5))
  df.loc[6,:] = df.loc[4,:]
  </code></pre>
  
  <p>However, when I attempt to do this for multiple rows, they are set to <code>NaN</code> rather than the rows I'm referencing:</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  
  df = pd.DataFrame(np.random.randn(10, 5))
  df.loc[5:6,:] = df.loc[3:4,:]
  </code></pre>
  
  <p>I have read through the documentation and cannot find an explanation.  Any ideas?  Thank you.</p>