title: Why doesn't the matplotlib label 'fontsize' work?
body: <p>I have used the following function, but the label size isn't changing. </p>
  
  <pre><code>axe.set_xlabel('$R^{-1}_m$ (nm$^{-1}$)')
  axe.xaxis.label.set_size(18)
  axe.set_ylabel('$E_{f}/l_{z}$ (eV/nm)',fontsize=40)
  axd.set_xlabel(r"$D$ (nm)",color='blue',fontsize=28)
  </code></pre>
  
  <p>I do not have enough reputation to post images. So I post it here: <a href="http://imgur.com/T2pbd9B" rel="noreferrer">http://imgur.com/T2pbd9B</a>
  The sizes of the three labels never change, no matter how much the 'fontsize' tag is.</p>
  
  <p>The original code is here:</p>
  
  <pre><code>from __future__ import division
  import numpy as np
  import matplotlib.pyplot as plt
  from mpl_toolkits.axes_grid1 import host_subplot
  import mpl_toolkits.axisartist as AA
  from matplotlib.patches import Rectangle
  
  colormap = {'0':'yellow','1':'Indigo','2':'pink','3':'blue','4':'magenta','5':'orange','6':'cyan','7':'chartreuse','8':'royalblue','9':'red','10':'navy',}
  markershape={'0':'o','1':vec1,'2':rotate_vec(vec2),'3':'^','4':'s','5':'p','6':'H','7':(7,0,0),'8':'8','9':(9,0,0),'10':(10,0,90),}
  mksz=12
  markersizemap={'0':mksz,'1':mksz*1.1,'2':mksz*1.1,'3':mksz*0.9,'4':mksz*0.8,'5':mksz,'6':mksz,'7':mksz,'8':mksz*1.1,'9':mksz*1.2,'10':mksz*1.2,}   
  fitxx = np.arange(4)    
  e_xmin=0.8;e_xmax=2.1;e_ymin=20;e_ymax=38
  
  fig=plt.figure(num=None, figsize=(8,6), dpi=110, facecolor='w', edgecolor='k') 
  ax0 = host_subplot(111, axes_class=AA.Axes)
  rec=Rectangle((e_xmin,e_ymin), e_xmax-e_xmin, e_ymax-e_ymin, ec="w",fc='lightgrey',alpha=0.4)
  ax0.add_patch(rec)
  for nn in range(len(lstall)):
      fityy=aaa(nn)*fitxx+bbb(nn)
      ax0.plot(fitxx,fityy,'--',color=colormap['%d'%nn],linewidth=2)
      ax0.plot(lstall[nn][:,0],lstall[nn][:,1],marker=markershape['%d'%nn],markersize=markersizemap['%d'%nn],color=colormap['%d'%nn],label="n={}".format(nn),linestyle='None')
  ax0.set_xlabel(r'$R^{-1}_m$ (nm$^{-1}$)')
  ax0.xaxis.label.set_size(18)
  ax0.set_ylabel(r'$E_{f}/l_{z}$ (eV/nm)',fontsize=100)
  xmax=2.1
  ax0.set_xlim((0, xmax));ax0.set_ylim((0, 62));ax0.grid(False)
  axd = ax0.twiny();axd.grid()
  dticklabels =['9','7','6','5','4','3','2','1.5','1','%.2f'%(2/xmax)] 
  def tick_function(X):
      V=[]
      for dd in X:
          kk = 2/float(dd)
          V.append(kk)       
      return V
  curvticks=tick_function(dticklabels)
  dticklabels.pop(-1)
  dticklabels.append(' ')
  axd.set_xticks(curvticks)
  axd.set_xticklabels(dticklabels)
  axd.set_xlabel(r"Diameter $D$ (nm)",color='blue',fontsize=28)
  fig.savefig('%s/data1.png'%path,bbox_inches='tight')
  fig.savefig('%s/data1.eps'%path,bbox_inches='tight')
  </code></pre>