title: add dictionary data to a pandas pandas dataframe overwriting values not loosing index
body: <p>Assuming I have a DF as follows:</p>
  <pre><code>df = pd.DataFrame({'legs': [2, 4, 8, 0],
                     'wings': [2, 0, 0, 0],
                     'specimen': [10, 2, 1, 8]},
                    index=['falcon', 'dog', 'spider', 'fish'])
  df
  </code></pre>
  <p>resulting in:</p>
  <p><a href="https://i.stack.imgur.com/FF64A.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FF64A.png" alt="enter image description here" /></a></p>
  <p>Now I get data in the form of a dict and I would like to add it</p>
  <pre><code>new_data = {'dog':{'wings':45,'specimen':89},'fish':{'wings':55555,'something_new':'new value'}, 'new_row':{'wings':90}}
  new_data_df = pd.DataFrame(new_data).T
  new_data_df
  </code></pre>
  <p>I can use append to add the data to the first DF, but append will be deprecated, so I rather stay away.
  I can use concat as in here:
  <a href="https://stackoverflow.com/questions/51774826/append-dictionary-to-data-frame">append dictionary to data frame</a></p>
  <pre><code>output = pd.concat([df, new_data_df], ignore_index=False)
  output
  </code></pre>
  <p>but this does not give the result required:
  <a href="https://i.stack.imgur.com/9o0qz.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9o0qz.png" alt="enter image description here" /></a></p>
  <p>I dont want row index to be duplicated. I would like that the data is overwriting and added when a new column or row appears in the dict.
  There should be one and only one dog index column.
  As you see in the above screenshot the row dog appears two times.</p>
  <p>changing ignore_index=False to True does not help, the index simple is skipped.</p>