title: Python Matplotlib, Stem plot not working with FuncAnimation
body: <p>I am trying to plot live data from incoming data packet. I have four subplots which on one of the subplot, i want to plot data as Stem plot however i am receiving following error:<br>
  <strong>self.stemlines.set_data(z, y)
  AttributeError: 'list' object has no attribute 'set_data'</strong></p>
  
  <p>plt.plot works fine but I am not able to get it to work for plt.steam.</p>
  
  <pre><code>import matplotlib
  
  matplotlib.use('Qt5Agg')
  import matplotlib.pyplot as plt
  from matplotlib.widgets import TextBox
  import matplotlib
  
  
  class PlotEngine:
  
      def __init__(self, axisChanged):
          # plt.style.use('seaborn-whitegrid')
          # style.use('fivethirtyeight')
          initialMinValue = '14.4'
          initialMaxValue = '14.9'
  
          plt.style.use('ggplot')
          matplotlib.rc('axes', titlesize=8)  # fontsize of the axes title
          matplotlib.rc('axes', labelsize=8)
          matplotlib.rc('xtick', labelsize=8)  # fontsize of the tick labels
          matplotlib.rc('ytick', labelsize=8)  # fontsize of the tick labels   axes.titlesize
          matplotlib.rc('figure', titlesize=8)
  
          self.fig, self.ax = plt.subplots(2, 2)
          plt.ion()
          # plt.subplot(2, 2, 4, polar=True)
          self.fig.patch.set_facecolor('gray')
          self.axpolar = plt.subplot(2, 2, 4, projection='polar')
          self.axpolar.set_facecolor('black')
          # self.ax[1, 1] = fig.add_subplot(2, 2, 4, projection='polar')
          self.ax[0, 0].set_facecolor('black')
          self.ax[0, 1].set_facecolor('black')
          self.ax[1, 0].set_facecolor('black')
          self.ax[1, 1].set_facecolor('black')
  
          self.axisChanged = axisChanged
          self.slider_freq = plt.axes([0.1, 0.01, 0.3, 0.01])
          self.slider_azi = plt.axes([0.5, 0.01, 0.3, 0.01])
          self.freqAxBoxMin = plt.axes([0.55, 0.33, 0.04, 0.03])
          self.freqAxBoxMax = plt.axes([0.55, 0.28, 0.04, 0.03])
          self.freqMinValueBox = TextBox(self.freqAxBoxMin, 'Min Freq:', initial=initialMinValue)
          self.freqMaxValueBox = TextBox(self.freqAxBoxMax, 'Max Freq:', initial=initialMaxValue)
          self.aziAxBoxMin = plt.axes([0.55, 0.18, 0.04, 0.03])
          self.aziAxBoxMax = plt.axes([0.55, 0.10, 0.04, 0.03])
          self.aziMinValueBox = TextBox(self.aziAxBoxMin, 'Min Dir:', initial='-180')
          self.aziMaxValueBox = TextBox(self.aziAxBoxMax, 'Max Dir:', initial='180')
          self.zeroOne, = self.ax[0, 1].plot([], [], 'ro')
          self.oneOne, = self.axpolar.plot([], [], 'ro')
          self.markerline, self.stemlines, self.baseline, = self.ax[1, 0].stem([1], [1], bottom=-140)
          self.ax[0, 1].set_xlim([0, 60])
          self.ax[0, 1].set_ylim([-140, -40])
          self.axpolar.set_yticks(range(-90, -30, 10))  # Define the yticks
          # self.axpolar.set_yticklabels(map(str, range(-90, -30, -10)))  # Change the labels
          self.ax[1, 0].set_xlim([14, 14.8])
          self.ax[1, 0].set_ylim([-140, -40])
  
      # self.background = fig.canvas.copy_from_bbox(self.ax.bbox)
  
      def animateZeroOne(self, i, azimuth, rss, freqGhz):
          x = azimuth
          y = rss
          z = freqGhz
  
          self.zeroOne.set_data(x, y)
          self.oneOne.set_data(x, y)
          self.stemlines.set_data(z, y)
          self.markerline.set_data(z, y)
  
          return self.zeroOne, self.oneOne, self.stemlines, self.markerline
  </code></pre>