title: tickformat in Plotly Python
body: <p>I am trying to format my Plotly Bar Chart x-axis to percentages with 3 decimal points. </p>
  
  <pre><code>import chart_studio.plotly as py #for plotting
  import plotly.graph_objs as go
  
  
  y = ['niner', 'deuce', 'checker']
  x = [0.03, -0.05, 0.075]
  
  
  fig = go.Figure(go.Bar(y = y, x = x,
              name = 'returns',
              orientation = 'h',
              marker = dict(color = '#003663',
                               line = dict(
                                        color = '#afafaf',
                                        width = 1.5)
                                      )))
  
  fig.update_layout(
          title = 'Why So Hard Plotly?',
          xaxis = dict(
                  tickformat = '%.format.%3f',
                  title = 'Returns',
                  fixedrange = True,
                  hoverformat = '.3f',
                  showgrid = True), 
  
          yaxis = dict(
  
                  fixedrange = True,
                  hoverformat = '.3f',
                  showgrid = True,
  
          ),     
           bargap = 0.2, 
           barmode = 'relative',             
  )
  fig.update_yaxes(automargin=True) 
  fig.show()
  </code></pre>
  
  <p>I can get the y-axis to appear as a rounded percentage using <code>tickformat = '%'</code>,
  but I can't get more decimals to appears. The Plotly d3 documentation isn't clear (to me) how to do this. Any help is appreciated.</p>
  
  <p>Thanks in advance.</p>