text: # version 1.0
  
  import numpy
  import pandas as pd
  import seaborn as sn
  import matplotlib.pyplot as plt
  import matplotlib.cm as cm
  from matplotlib.colors import ListedColormap, BoundaryNorm
  from sklearn import neighbors
  import matplotlib.patches as mpatches
  import graphviz
  from sklearn.tree import export_graphviz
  import matplotlib.patches as mpatches
  
  def load_crime_dataset():
      # Communities and Crime dataset for regression
      # https://archive.ics.uci.edu/ml/datasets/Communities+and+Crime+Unnormalized
  
      crime = pd.read_table('Crime_Data.csv', sep=',', na_values='?')
      # remove features with poor coverage or lower relevance, and keep ViolentCrimesPerPop target column
      columns_to_keep = [5, 6] + list(range(11,26)) + list(range(32, 103)) + [145]  
      crime = crime.iloc[:,columns_to_keep].dropna()
  
      X_crime = crime.iloc[:,range(0,88)]
      y_crime = crime['violentPerPop']
  
      return (X_crime, y_crime)
  
  def plot_decision_tree(clf, feature_names, class_names):
      # This function requires the pydotplus module and assumes it's been installed.
      # In some cases (typically under Windows) even after running conda install, there is a problem where the
      # pydotplus module is not found when running from within the notebook environment.  The following code
      # may help to guarantee the module is installed in the current notebook environment directory.
      #
      # import sys; sys.executable
      # !{sys.executable} -m pip install pydotplus
  
      export_graphviz(clf, out_file="adspy_temp.dot", feature_names=feature_names, class_names=class_names, filled = True, impurity = False)
      with open("adspy_temp.dot") as f:
          dot_graph = f.read()
      # Alternate method using pydotplus, if installed.
      # graph = pydotplus.graphviz.graph_from_dot_data(dot_graph)
      # return graph.create_png()
      return graphviz.Source(dot_graph)
  
  def plot_feature_importances(clf, feature_names):
      c_features = len(feature_names)
      plt.barh(range(c_features), clf.feature_importances_)
      plt.xlabel("Feature importance")
      plt.ylabel("Feature name")
      plt.yticks(numpy.arange(c_features), feature_names)
  
  def plot_labelled_scatter(X, y, class_labels):
      num_labels = len(class_labels)
  
      x_min, x_max = X[:, 0].min() - 1, X[:, 0].max() + 1
      y_min, y_max = X[:, 1].min() - 1, X[:, 1].max() + 1
  
      marker_array = ['o', '^', '*']
      color_array = ['#FFFF00', '#00AAFF', '#000000', '#FF00AA']
      cmap_bold = ListedColormap(color_array)
      bnorm = BoundaryNorm(numpy.arange(0, num_labels + 1, 1), ncolors=num_labels)
      plt.figure()
  
      plt.scatter(X[:, 0], X[:, 1], s=65, c=y, cmap=cmap_bold, norm = bnorm, alpha = 0.40, edgecolor='black', lw = 1)
  
      plt.xlim(x_min, x_max)
      plt.ylim(y_min, y_max)
  
      h = []
      for c in range(0, num_labels):
          h.append(mpatches.Patch(color=color_array[c], label=class_labels[c]))
      plt.legend(handles=h)
  
      plt.show()
  
  
  def plot_class_regions_for_classifier_subplot(clf, X, y, X_test, y_test, title, subplot, target_names = None, plot_decision_regions = True):
  
      numClasses = numpy.amax(y) + 1
      color_list_light = ['#FFFFAA', '#EFEFEF', '#AAFFAA', '#AAAAFF']
      color_list_bold = ['#EEEE00', '#000000', '#00CC00', '#0000CC']
      cmap_light = ListedColormap(color_list_light[0:numClasses])
      cmap_bold  = ListedColormap(color_list_bold[0:numClasses])
  
      h = 0.03
      k = 0.5
      x_plot_adjust = 0.1
      y_plot_adjust = 0.1
      plot_symbol_size = 50
  
      x_min = X[:, 0].min()
      x_max = X[:, 0].max()
      y_min = X[:, 1].min()
      y_max = X[:, 1].max()
      x2, y2 = numpy.meshgrid(numpy.arange(x_min-k, x_max+k, h), numpy.arange(y_min-k, y_max+k, h))
  
      P = clf.predict(numpy.c_[x2.ravel(), y2.ravel()])
      P = P.reshape(x2.shape)
  
      if plot_decision_regions:
          subplot.contourf(x2, y2, P, cmap=cmap_light, alpha = 0.8)
  
      subplot.scatter(X[:, 0], X[:, 1], c=y, cmap=cmap_bold, s=plot_symbol_size, edgecolor = 'black')
      subplot.set_xlim(x_min - x_plot_adjust, x_max + x_plot_adjust)
      subplot.set_ylim(y_min - y_plot_adjust, y_max + y_plot_adjust)
  
      if (X_test is not None):
          subplot.scatter(X_test[:, 0], X_test[:, 1], c=y_test, cmap=cmap_bold, s=plot_symbol_size, marker='^', edgecolor = 'black')
          train_score = clf.score(X, y)
          test_score  = clf.score(X_test, y_test)
          title = title + "\nTrain score = {:.2f}, Test score = {:.2f}".format(train_score, test_score)
  
      subplot.set_title(title)
  
      if (target_names is not None):
          legend_handles = []
          for i in range(0, len(target_names)):
              patch = mpatches.Patch(color=color_list_bold[i], label=target_names[i])
              legend_handles.append(patch)
          subplot.legend(loc=0, handles=legend_handles)
  
  
  def plot_class_regions_for_classifier(clf, X, y, X_test=None, y_test=None, title=None, target_names = None, plot_decision_regions = True):
  
      numClasses = numpy.amax(y) + 1
      color_list_light = ['#FFFFAA', '#EFEFEF', '#AAFFAA', '#AAAAFF']
      color_list_bold = ['#EEEE00', '#000000', '#00CC00', '#0000CC']
      cmap_light = ListedColormap(color_list_light[0:numClasses])
      cmap_bold  = ListedColormap(color_list_bold[0:numClasses])
  
      h = 0.03
      k = 0.5
      x_plot_adjust = 0.1
      y_plot_adjust = 0.1
      plot_symbol_size = 50
  
      x_min = X[:, 0].min()
      x_max = X[:, 0].max()
      y_min = X[:, 1].min()
      y_max = X[:, 1].max()
      x2, y2 = numpy.meshgrid(numpy.arange(x_min-k, x_max+k, h), numpy.arange(y_min-k, y_max+k, h))
  
      P = clf.predict(numpy.c_[x2.ravel(), y2.ravel()])
      P = P.reshape(x2.shape)
      plt.figure()
      if plot_decision_regions:
          plt.contourf(x2, y2, P, cmap=cmap_light, alpha = 0.8)
  
      plt.scatter(X[:, 0], X[:, 1], c=y, cmap=cmap_bold, s=plot_symbol_size, edgecolor = 'black')
      plt.xlim(x_min - x_plot_adjust, x_max + x_plot_adjust)
      plt.ylim(y_min - y_plot_adjust, y_max + y_plot_adjust)
  
      if (X_test is not None):
          plt.scatter(X_test[:, 0], X_test[:, 1], c=y_test, cmap=cmap_bold, s=plot_symbol_size, marker='^', edgecolor = 'black')
          train_score = clf.score(X, y)
          test_score  = clf.score(X_test, y_test)
          title = title + "\nTrain score = {:.2f}, Test score = {:.2f}".format(train_score, test_score)
  
      if (target_names is not None):
          legend_handles = []
          for i in range(0, len(target_names)):
              patch = mpatches.Patch(color=color_list_bold[i], label=target_names[i])
              legend_handles.append(patch)
          plt.legend(loc=0, handles=legend_handles)
  
      if (title is not None):
          plt.title(title)
      plt.show()
      
  def plot_fruit_knn(X, y, n_neighbors, weights):
      X_mat = X[['height', 'width']].as_matrix()
      y_mat = y.as_matrix()
  
      # Create color maps
      cmap_light = ListedColormap(['#FFAAAA', '#AAFFAA', '#AAAAFF','#AFAFAF'])
      cmap_bold  = ListedColormap(['#FF0000', '#00FF00', '#0000FF','#AFAFAF'])
  
      clf = neighbors.KNeighborsClassifier(n_neighbors, weights=weights)
      clf.fit(X_mat, y_mat)
  
      # Plot the decision boundary by assigning a color in the color map
      # to each mesh point.
      
      mesh_step_size = .01  # step size in the mesh
      plot_symbol_size = 50
      
      x_min, x_max = X_mat[:, 0].min() - 1, X_mat[:, 0].max() + 1
      y_min, y_max = X_mat[:, 1].min() - 1, X_mat[:, 1].max() + 1
      xx, yy = numpy.meshgrid(numpy.arange(x_min, x_max, mesh_step_size),
                           numpy.arange(y_min, y_max, mesh_step_size))
      Z = clf.predict(numpy.c_[xx.ravel(), yy.ravel()])
  
      # Put the result into a color plot
      Z = Z.reshape(xx.shape)
      plt.figure()
      plt.pcolormesh(xx, yy, Z, cmap=cmap_light)
  
      # Plot training points
      plt.scatter(X_mat[:, 0], X_mat[:, 1], s=plot_symbol_size, c=y, cmap=cmap_bold, edgecolor = 'black')
      plt.xlim(xx.min(), xx.max())
      plt.ylim(yy.min(), yy.max())
  
      patch0 = mpatches.Patch(color='#FF0000', label='apple')
      patch1 = mpatches.Patch(color='#00FF00', label='mandarin')
      patch2 = mpatches.Patch(color='#0000FF', label='orange')
      patch3 = mpatches.Patch(color='#AFAFAF', label='lemon')
      plt.legend(handles=[patch0, patch1, patch2, patch3])
  
          
      plt.xlabel('height (cm)')
      plt.ylabel('width (cm)')
      
      plt.show()
  
  def plot_two_class_knn(X, y, n_neighbors, weights, X_test, y_test):
      X_mat = X
      y_mat = y
  
      # Create color maps
      cmap_light = ListedColormap(['#FFFFAA', '#AAFFAA', '#AAAAFF','#EFEFEF'])
      cmap_bold  = ListedColormap(['#FFFF00', '#00FF00', '#0000FF','#000000'])
  
      clf = neighbors.KNeighborsClassifier(n_neighbors, weights=weights)
      clf.fit(X_mat, y_mat)
  
      # Plot the decision boundary by assigning a color in the color map
      # to each mesh point.
      
      mesh_step_size = .01  # step size in the mesh
      plot_symbol_size = 50
      
      x_min, x_max = X_mat[:, 0].min() - 1, X_mat[:, 0].max() + 1
      y_min, y_max = X_mat[:, 1].min() - 1, X_mat[:, 1].max() + 1
      xx, yy = numpy.meshgrid(numpy.arange(x_min, x_max, mesh_step_size),
                           numpy.arange(y_min, y_max, mesh_step_size))
      Z = clf.predict(numpy.c_[xx.ravel(), yy.ravel()])
  
      # Put the result into a color plot
      Z = Z.reshape(xx.shape)
      plt.figure()
      plt.pcolormesh(xx, yy, Z, cmap=cmap_light)
  
      # Plot training points
      plt.scatter(X_mat[:, 0], X_mat[:, 1], s=plot_symbol_size, c=y, cmap=cmap_bold, edgecolor = 'black')
      plt.xlim(xx.min(), xx.max())
      plt.ylim(yy.min(), yy.max())
  
      title = "Neighbors = {}".format(n_neighbors)
      if (X_test is not None):
          train_score = clf.score(X_mat, y_mat)
          test_score  = clf.score(X_test, y_test)
          title = title + "\nTrain score = {:.2f}, Test score = {:.2f}".format(train_score, test_score)
  
      patch0 = mpatches.Patch(color='#FFFF00', label='class 0')
      patch1 = mpatches.Patch(color='#000000', label='class 1')
      plt.legend(handles=[patch0, patch1])
  
      plt.xlabel('Feature 0')
      plt.ylabel('Feature 1')
      plt.title(title)
  
      plt.show()
  