title: matplotlib colorbar formatting
body: <p>I've been python code to plot 4 figures with colorbars. Since I use Texfonts, matplotlib renders the minus sign too wide. I therefore have a written a formatting function to replace the minus sign with a hyphen.
  However, for some reason I can't apply the formatter to my colorbar.
  I am getting an error:</p>
  
  <pre><code>cb.ax.set_major_formatter(ticker.FuncFormatter(myfmt))
  AttributeError: 'AxesSubplot' object has no attribute 'set_major_formatter'
  </code></pre>
  
  <p>So below is the portion of my code where it breaks:
  Do you have an idea how to force the colorbar to use my formatting function?</p>
  
  <pre><code>#!/usr/bin/env python3 
  
  import re
  import numpy as np
  import matplotlib.pyplot as plt
  from matplotlib import rc 
  from matplotlib.ticker import *
  import matplotlib.ticker as ticker
  import matplotlib as mpl
  import matplotlib.gridspec as gridspec
  from matplotlib.patches import Ellipse
  from list2nparr import list2nparr
  from matplotlib.ticker import ScalarFormatter 
  
  plt.rcParams['text.usetex'] = True
  plt.rcParams['font.family'] = 'serif'
  plt.rcParams['font.serif'] = 'cm'
  plt.rcParams['font.size'] = 16
  #plt.rcParams['font.weight'] = 'heavy'
  plt.rcParams['axes.unicode_minus'] = False
  #-----------------------------------------------------
  
  
  def myfmt(x, pos=None):
    rv = format(x)
    if mpl.rcParams["text.usetex"]:
      rv = re.sub('$-$', r'\mhyphen', rv)
  
    return rv
  
  
  fig,(ax1,ax2,ax3,ax4) = plt.subplots(nrows=4,figsize=(6,11),sharex = True, sharey=False)
  data = list2nparr('radiant.txt')
  
  lm  = data[:,14]
  bet = data[:,15]
  v   = data[:,16]
  b   = data[:,18]
  ejep = data[:,20]
  
  fig.subplots_adjust(hspace=0.1)
  
  cm = plt.cm.get_cmap('jet') 
  sc = ax1.scatter(lm, bet, c=ejep, s=10, cmap=cm, edgecolor='none',rasterized=True)
  cb=plt.colorbar(sc,ax = ax1,aspect=10)
  cb.formatter.set_powerlimits((0, 0))
  cb.ax.set_major_formatter(ticker.FuncFormatter(myfmt))
  cb.update_ticks()
  </code></pre>