title: Can't render a matplotlib graph using Qt5Agg backend
body: <p>I'm trying to make this script work, but whenever I run it in the terminal, it doesn't render even if the script is still running.</p>
  
  <p>I installed Qt5Agg using </p>
  
  <pre><code>pip install Qt5Agg 
  </code></pre>
  
  <p>I'm on a windows 10 computer.<br>
  I use python 3.5<br>
  I've got no error in the terminal.<br>
  I've got all the needed dependencies for the script.  </p>
  
  <p>Here is the script:</p>
  
  <pre><code>import csv
  import numpy as np
  from sklearn.svm import SVR
  import matplotlib.pyplot as plt
  
  
  plt.switch_backend('Qt5Agg')
  
  
  
  dates = []
  prices = []
  
  def get_data(filename):
      with open(filename, 'r') as csvfile:
          csvFileReader = csv.reader(csvfile)
          next(csvFileReader) # skipping column names
          for row in csvFileReader:
              dates.append(int(row[0].split('-')[0]))
              prices.append(float(row[1]))
      return
  
  def predict_price(dates, prices, x):
      dates = np.reshape(dates,(len(dates), 1)) # converting to matrix of n X 1
  
      svr_lin = SVR(kernel= 'linear', C= 1e3)
      svr_poly = SVR(kernel= 'poly', C= 1e3, degree= 2)
      svr_rbf = SVR(kernel= 'rbf', C= 1e3, gamma= 0.1) # defining the support vector regression models
      svr_rbf.fit(dates, prices) # fitting the data points in the models
      svr_lin.fit(dates, prices)
      svr_poly.fit(dates, prices)
  
      plt.scatter(dates, prices, color= 'black', label= 'Data') # plotting the initial datapoints
      plt.plot(dates, svr_rbf.predict(dates), color= 'red', label= 'RBF model') # plotting the line made by the RBF kernel
      plt.plot(dates,svr_lin.predict(dates), color= 'green', label= 'Linear model') # plotting the line made by linear kernel
      plt.plot(dates,svr_poly.predict(dates), color= 'blue', label= 'Polynomial model') # plotting the line made by polynomial kernel
      plt.xlabel('Date')
      plt.ylabel('Price')
      plt.title('Support Vector Regression')
      plt.legend()
      plt.show()
  
      return svr_rbf.predict(x)[0], svr_lin.predict(x)[0], svr_poly.predict(x)[0]
  
  get_data('deutch.csv') # calling get_data method by passing the csv file to it
  #print "Dates- ", dates
  #print "Prices- ", prices
  
  predicted_price = predict_price(dates, prices, 40)
  
  print(predicted_price)
  </code></pre>