title: Minor ticks in pandas plot
body: <p>So I am trying to get minor tick grid lines to get displayed but they don't seem to appear on the plot. An example code is </p>
  
  <pre><code>data_temp = pd.read_csv(dir_readfile, dtype=float, delimiter='\t', 
                      names = names, usecols=[0,1,2,3,4])
  
  result = data_temp.groupby(['A', 'D']).agg({'B':'mean', 'E':'mean'})
  result2 = result.unstack()
  
  x = np.arange(450, 700, 50, dtype = int)
  plt.grid(True, which='both')
  plt.minorticks_on()
  
  result2.B.plot(lw=2,colormap='jet',marker='.',markersize=4, 
                    title='A v/s B', legend = True, grid = 'on' ,
                    xlim = [450, 700], ylim = [-70, -0], xticks = x)
  </code></pre>
  
  <p>What I get is</p>
  
  <p><a href="https://i.stack.imgur.com/pGEeW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pGEeW.png" alt="Plot"></a></p>
  
  <p>The major grid lines are displayed but the minor ones are not. I looked into the pandas documentation but just see the grid option. I was hoping to get the minor ticks grid lines to be a every 10th location on the X axis that is 460 470 etc and every location on the Y (actual scale of Y is a bit smaller)</p>