未定义全局名称“tkagg”

Question

我知道这是一个常见的问题，我已经阅读了所有与此错误相关的链接。我意识到我必须把matplotlib.use（）放在pyplot等导入之前，但它仍然不起作用。我正在使用jupyter notebook和python 2.7。这些都是我导入的：

import Tkinter as tk
from Tkinter import*
import tkMessageBox
import tkFileDialog
import pandas as pd
import matplotlib
matplotlib.use('tkagg')
from PIL import Image, ImageTk
from tkinter import ttk
import pylab as plt
from matplotlib.ticker import (MultipleLocator, FormatStrFormatter,
                               AutoMinorLocator)
from matplotlib.figure import Figure
import seaborn as sns
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
from collections import Counter
try: 
    from matplotlib.backends.backend_tkagg import NavigationToolbar2Tk as PlotNav
except: 
    from matplotlib.backends.backend_tkagg import NavigationToolbar2TkAgg as PlotNav

这个函数在其中使用tkagg来提供导航工具栏：

def monthly_sells(array,hh): 
        monse = tk.Toplevel(hh)
        array['monthj'] = pd.to_numeric(array['monthj'])
        x=array['monthj'].values.tolist()
        x.sort(key=int)
        f = Figure(figsize=(4,3), dpi=80)
        f.add_axes([0.2, 0.15,0.78,0.7])
        canvas = FigureCanvasTkAgg(f, master=monse)
        canvas.get_tk_widget().grid(row=1, column=3, rowspan=6)
        tkagg.PlotNav(canvas, monse)

        p = f.gca()
        bins=[1,2,3,4,5,6,7,8,9,10,11,12,13]
        p.hist(x,bins,rwidth=0.8, label='sales amount in different months of year' )
        p.set_xlabel('month', fontsize = 10)
        p.set_ylabel('number of orders', fontsize = 10)

当我单击使用函数作为命令的按钮时，会发生此错误

global name 'tkagg' is not defined