title: In pandas how to create a new column from part of another, obeying a condition?
body: <p>In python 3 and pandas I have the dataframe:</p>
  
  <pre><code>lista_projetos.info()
  &lt;class 'pandas.core.frame.DataFrame'&gt;
  RangeIndex: 59 entries, 0 to 58
  Data columns (total 14 columns):
  n_projeto                             59 non-null object
  autor                                 59 non-null object
  ementa                                59 non-null object
  resumo                                59 non-null object
  votacao_nominal                       59 non-null object
  votacao_nominal_alternativa_emenda    59 non-null object
  link_votacao                          0 non-null float64
  observacao                            0 non-null float64
  link_emenda                           0 non-null float64
  indicado_por                          59 non-null object
  entidade_que_avalia                   59 non-null object
  favoravel_desfavoravel_indiferente    59 non-null object
  explicacao                            59 non-null object
  link_projeto                          59 non-null object
  dtypes: float64(3), object(11)
  memory usage: 6.5+ KB
  </code></pre>
  
  <p>The column "link_projeto" has urls, always in this format:</p>
  
  <p>"<a href="http://www.camara.gov.br/proposicoesWeb/fichadetramitacao?idProposicao=2171854" rel="nofollow noreferrer">http://www.camara.gov.br/proposicoesWeb/fichadetramitacao?idProposicao=2171854</a>"</p>
  
  <p>"<a href="http://www.camara.gov.br/proposicoesWeb/fichadetramitacao?idProposicao=2147513" rel="nofollow noreferrer">http://www.camara.gov.br/proposicoesWeb/fichadetramitacao?idProposicao=2147513</a>"</p>
  
  <p>"<a href="http://www.camara.gov.br/proposicoesWeb/fichadetramitacao?idProposicao=2168253" rel="nofollow noreferrer">http://www.camara.gov.br/proposicoesWeb/fichadetramitacao?idProposicao=2168253</a>"</p>
  
  <p>I want to create a new column from the "link_projeto" column. So: always pick up the final number after the "=" sign</p>
  
  <p>Like this:</p>
  
  <pre><code>new_column
  2171854
  2147513
  2168253
  </code></pre>
  
  <p>Please, is there a way to create a new column from part of another?</p>