title: Insert a blank column in dataframe
body: <p>I would like to insert a blank column in between "Delta = delta" and "Card = vars" in the dataframe below.  I would also like to sort the output by the column "Model_Avg_Error" in the dataframe as well.</p>
  
  <pre><code>df = data.frame(Card = vars, Model_Avg_Error = model_error, Forecast = forecasts,  Delta = delta, ,Card = vars, Model_Avg_Error = model_error, 
                  Forecast = forecasts,  Delta = delta)
  
  # save
  write.csv(df, file = file.path(proj_path, "output.csv"), row.names = F)
  </code></pre>
  
  <p>This was the error received from above:</p>
  
  <p>Error in data.frame(Card = vars, Model_Avg_Error = model_error, Forecast = forecasts,  : 
    argument is missing, with no default</p>