数据预处理
拆分数据集
选择最好的预测诊断算法
算法融合
数据探索见：python：乳腺癌预测之数据探索
实验器材
● UCI
● python
● seaborn
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实验内容
数据预处理
对诊断结果进行二值话，方便适应所有的预测算法。同时采用 preprocessing.scale 进行量化处理
拆分数据集
按照80/20方式，拆分训练集和测试机。 训练集按照交叉验证方式进行训练。
train_x1, test_x1,train_y, test_y = train_test_split(x_value_scaled, y_values,test_size=0.2)
选择最好的预测诊断算法
本次实验分别实验了 逻辑回归，随机森林，svm，线性SVM，决策树，高斯贝叶斯，梯度迭代决策树 几种算法。并利用learning_curve来判断是否过拟合。
本次预测实验的评价标准为预测精确度。
先来定义几个常用的函数
learning_curve
混淆矩阵
不同的算法精确度比较，精确度分别计算训练集的精确度和十折交叉的精确度
1
来看看初步的算法筛选
总体上看逻辑回归，svm 效果是最好的。看看是不是存在过拟合的情况
并没有存在过拟合的情况。
随机森林和决策树（未调参）情况下，存在一定的过拟合情况。
2
超参数调整
从上面的实验情况看，LR和SVM是比较好的精度。现在来进一步调整下这两个算法的超参数。
SVM超参数选择：
C : float, optional (default=1.0)
Penalty parameter C of the error term. C越小决策平面越光滑，因为对误分类的惩罚较小，C越大越倾向于精确地分类，并且此时有更多的自由去选择更多的向量作为支持向量
kernel : string, optional (default=’rbf’)
Specifies the kernel type to be used in the algorithm. It must be one of ‘linear’, ‘poly’, ‘rbf’, ‘sigmoid’, ‘precomputed’ or a callable. If none is given, ‘rbf’ will be used. If a callable is given it is used to pre-compute the kernel matrix from data matrices; that matrix should be an array of shape (n_samples, n_samples).
在测试集上，有3个恶性的被判定为良性。
LR超参数
C : float, default: 1.0 含义如SVM的C
Inverse of regularization strength; must be a positive float. Like in support vector machines, smaller values specify stronger regularization.
测试集合判断的情况是一样的。
3
算法融合
采用VotingClassifier的硬分类方式。采用SVM和LR融合
可以加入不同方式的算法来进一步融合，这里选择KNN
在多次数据拆分训练集和测试集，下融合svm+LR+KNN可以达到99%的预测率。
另外实验过程中还去除了相关性较强的几个熟悉，并没有对选用的算法并没有影响。
实验结语
本实验『WedO实验君』和大家一个做了乳腺癌的预测，采用不同的算法融合的策略。关键点为：过拟合判断，超参数筛选，算法融合。
附上jupyter notebook代码
# coding: utf-8
# In[1]:
import itertools
import pandas as pd
import numpy as np
import seaborn as sns
import matplotlib.pyplot as plt
from sklearn import preprocessing
from sklearn import model_selection
from sklearn.model_selection import train_test_split
from sklearn.decomposition import PCA
from sklearn.metrics import confusion_matrix, make_scorer, accuracy_score
from sklearn.model_selection import GridSearchCV, learning_curve
from sklearn.linear_model import LogisticRegression
from sklearn.tree import DecisionTreeClassifier
from sklearn.neighbors import KNeighborsClassifier
from sklearn.discriminant_analysis import LinearDiscriminantAnalysis
from sklearn.naive_bayes import GaussianNB
from sklearn.svm import SVC, LinearSVC
from sklearn.ensemble import RandomForestClassifier, GradientBoostingClassifier, VotingClassifier
from sklearn.neural_network import MLPClassifier as MLPC
get_ipython().run_line_magic('matplotlib', 'inline')
# In[2]:
data = pd.read_csv('f:/dm/data.csv')
col = data.columns
col
# In[3]:
data.isnull().sum()
# In[4]:
data.head()
# In[5]:
data.info()
# In[6]:
x_values = data.drop(['diagnosis','id'], axis = 1)
y_values = data['diagnosis']
# In[7]:
data.describe()
# In[8]:
def plot_box(data, cols = 3):
size = len(data.columns)
rows = size//cols + 1
fig = plt.figure(figsize=(13,10))
cnt = 1
for col_name in data.columns:
ax = fig.add_subplot(rows,cols,cnt)
plt.boxplot(data[col_name])
ax.set_xlabel(col_name)
cnt = cnt + 1
plt.tight_layout()
plt.show()
plot_box(x_values.iloc[:,0:8], 4)
# In[9]:
plot_box(x_values.iloc[:,8:16], 4)
# In[10]:
plot_box(x_values.iloc[:,16:32], 4)
# In[11]:
def plot_distribution(data, target_col):
sns.set_style("whitegrid")
for col_name in data.columns:
if col_name != target_col:
title=("# of %s vs %s " % (col_name, target_col))
distributionOne = sns.FacetGrid(data, hue=target_col,aspect=2.5)
distributionOne.map(plt.hist, col_name, bins=30)
distributionOne.add_legend()
distributionOne.set_axis_labels(col_name, 'Count')
distributionOne.fig.suptitle(title)
distributionTwo = sns.FacetGrid(data, hue=target_col,aspect=2.5)
distributionTwo.map(sns.kdeplot,col_name,shade= True)
distributionTwo.set(xlim=(0, data[col_name].max()))
distributionTwo.add_legend()
distributionTwo.set_axis_labels(col_name, 'Proportion')
distributionTwo.fig.suptitle(title)
plot_distribution(data, 'diagnosis')
# In[12]:
g = sns.heatmap(x_values.corr(),cmap="BrBG",annot=False)
# In[13]:
plot_distribution(data[( data['area_mean'] > 500 ) & (data['area_mean'] < 800)], 'diagnosis')
# In[14]:
g = sns.heatmap(x_values.iloc[:,1:10].corr(),cmap="BrBG",annot=False)
# In[15]:
def diagnosis_to_binary(data):
data["diagnosis"] = data["diagnosis"].astype("category")
data["diagnosis"].cat.categories = [0,1]
data["diagnosis"] = data["diagnosis"].astype("int")
diagnosis_to_binary(data)
x_values = data.drop(['diagnosis','id'], axis = 1)
y_values = data['diagnosis']
x_value_scaled = preprocessing.scale(x_values)
x_value_scaled = pd.DataFrame(x_value_scaled, columns = x_values.columns, index=data["id"])
x_value_all = x_value_scaled
#x_value_all['diag'] = y_values.tolist()
#x_value_all.head()
# In[16]:
#x_value_scaled.groupby([u'diag']).agg({ 'compactness_mean': [np.mean]}).reset_index()
# In[17]:
variance_pct = .99 # Minimum percentage of variance we want to be described by the resulting transformed components
pca = PCA(n_components=variance_pct) # Create PCA object
x_transformed = pca.fit_transform(x_value_scaled,y_values) # Transform the initial features
x_values_scaled_PCA = pd.DataFrame(x_transformed) # Create a data frame from the PCA'd data
# In[18]:
g = sns.heatmap(x_values_scaled_PCA.corr(),cmap="BrBG",annot=False)
# ## 拆分数据集合
# In[19]:
x_value_scaled.head()
# In[20]:
y_values.head()
# In[21]:
def plot_learning_curve(estimator, title, X, y, ylim=None, cv=None,
n_jobs=1, train_sizes=np.linspace(.1, 1.0, 5)):
"""
Plots a learning curve. http://scikit-learn.org/stable/modules/learning_curve.html
"""
plt.figure()
plt.title(title)
if ylim is not None:
plt.ylim(*ylim)
plt.xlabel("Training examples")
plt.ylabel("Score")
train_sizes, train_scores, test_scores = learning_curve(
estimator, X, y, cv=cv, n_jobs=n_jobs, train_sizes=train_sizes)
train_scores_mean = np.mean(train_scores, axis=1)
train_scores_std = np.std(train_scores, axis=1)
test_scores_mean = np.mean(test_scores, axis=1)
test_scores_std = np.std(test_scores, axis=1)
plt.grid()
plt.fill_between(train_sizes, train_scores_mean - train_scores_std,
train_scores_mean + train_scores_std, alpha=0.1,
color="r")
plt.fill_between(train_sizes, test_scores_mean - test_scores_std,
test_scores_mean + test_scores_std, alpha=0.1, color="g")
plt.plot(train_sizes, train_scores_mean, 'o-', color="r",
label="Training score")
plt.plot(train_sizes, test_scores_mean, 'o-', color="g",
label="Cross-validation score")
plt.legend(loc="best")
return plt
def plot_confusion_matrix(cm, classes,
normalize=False,
title='Confusion matrix',
cmap=plt.cm.Blues):
"""
http://scikit-learn.org/stable/auto_examples/model_selection/plot_confusion_matrix.html
"""
if normalize:
cm = cm.astype('float') / cm.sum(axis=1)[:, np.newaxis]
print("Normalized confusion matrix")
else:
print('Confusion matrix, without normalization')
print(cm)
plt.imshow(cm, interpolation='nearest', cmap=cmap)
plt.title(title)
plt.colorbar()
tick_marks = np.arange(len(classes))
plt.xticks(tick_marks, classes, rotation=45)
plt.yticks(tick_marks, classes)
fmt = '.2f' if normalize else 'd'
thresh = cm.max() / 2.
for i, j in itertools.product(range(cm.shape[0]), range(cm.shape[1])):
plt.text(j, i, format(cm[i, j], fmt),
horizontalalignment="center",
color="white" if cm[i, j] > thresh else "black")
plt.tight_layout()
plt.ylabel('True label')
plt.xlabel('Predicted label')
dict_characters = {1: 'Malignant', 0: 'Benign'}
# In[22]:
def compareABunchOfDifferentModelsAccuracy(a, b, c, d):
"""
compare performance of classifiers on X_train, X_test, Y_train, Y_test
http://scikit-learn.org/stable/modules/generated/sklearn.metrics.accuracy_score.html#sklearn.metrics.accuracy_score
http://scikit-learn.org/stable/modules/model_evaluation.html#accuracy-score
"""
print(' Compare Multiple Classifiers: ')
print('K-Fold Cross-Validation Accuracy: ')
names = []
models = []
resultsAccuracy = []
models.append(('LR', LogisticRegression()))
models.append(('RF', RandomForestClassifier()))
models.append(('KNN', KNeighborsClassifier()))
models.append(('SVM', SVC()))
models.append(('LSVM', LinearSVC()))
models.append(('GNB', GaussianNB()))
models.append(('DTC', DecisionTreeClassifier()))
models.append(('GBC', GradientBoostingClassifier()))
for name, model in models:
plot_learning_curve(model, 'Learning Curve For %s Classifier'% (name), a,b, (0.8,1.1), 10)
for name, model in models:
model.fit(a, b)
kfold = model_selection.KFold(n_splits=10, random_state=7)
accuracy_results = model_selection.cross_val_score(model, a,b, cv=kfold, scoring='accuracy')
resultsAccuracy.append(accuracy_results)
names.append(name)
accuracyMessage = "%s: %f (%f)" % (name, accuracy_results.mean(), accuracy_results.std())
print(accuracyMessage)
# Boxplot
fig = plt.figure()
fig.suptitle('Algorithm Comparison: Accuracy')
ax = fig.add_subplot(111)
plt.boxplot(resultsAccuracy)
ax.set_xticklabels(names)
ax.set_ylabel('Cross-Validation: Accuracy Score')
plt.show()
# In[56]:
train_x1, test_x1,train_y, test_y = train_test_split(x_value_scaled, y_values,test_size=0.2)
# In[57]:
train_x1.columns
# In[58]:
#'texture_se','texture_worst'
drop_list = []
train_x = train_x1.drop(drop_list, axis = 1)
test_x = test_x1.drop(drop_list, axis = 1)
# In[59]:
compareABunchOfDifferentModelsAccuracy(train_x, train_y,None, None)
# In[60]:
def selectParametersForSVM(a, b, c, d):
model = SVC()
parameters = {'C': [ 0.01,0.1, 0.5, 1.0, 5.0, 10, 25, 50, 100],
'kernel': ['linear', 'poly', 'rbf', 'sigmoid']}
accuracy_scorer = make_scorer(accuracy_score)
grid_obj = GridSearchCV(model, parameters, scoring=accuracy_scorer)
grid_obj = grid_obj.fit(a, b)
model = grid_obj.best_estimator_
model.fit(a, b)
print('Selected Parameters for SVM: ')
print(model," ")
kfold = model_selection.KFold(n_splits=10, random_state=7)
accuracy = model_selection.cross_val_score(model, a,b, cv=kfold, scoring='accuracy')
mean = accuracy.mean()
stdev = accuracy.std()
print('Support Vector Machine - Training set accuracy: %s (%s)' % (mean, stdev))
print('')
prediction = model.predict(c)
#print(prediction[0])
cnf_matrix = confusion_matrix(d, prediction)
np.set_printoptions(precision=2)
class_names = dict_characters
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names,title='Confusion matrix')
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names, normalize=True,
title='Normalized confusion matrix')
plot_learning_curve(model, 'Learning Curve For SVM Classifier', a, b, (0.85,1.1), 10)
return prediction
# In[61]:
def selectParametersForLR(a, b, c, d):
model = LogisticRegression()
parameters = {'C': [ 0.01,0.1, 0.5, 1.0, 5.0, 10, 25, 50, 100]}
accuracy_scorer = make_scorer(accuracy_score)
grid_obj = GridSearchCV(model, parameters, scoring=accuracy_scorer)
grid_obj = grid_obj.fit(a, b)
model = grid_obj.best_estimator_
model.fit(a, b)
print('Selected Parameters for LR: ')
print(model," ")
kfold = model_selection.KFold(n_splits=10, random_state=7)
accuracy = model_selection.cross_val_score(model, a,b, cv=kfold, scoring='accuracy')
mean = accuracy.mean()
stdev = accuracy.std()
print('Support Vector Machine - Training set accuracy: %s (%s)' % (mean, stdev))
print('')
prediction = model.predict(c)
#print(prediction[0])
cnf_matrix = confusion_matrix(d, prediction)
np.set_printoptions(precision=2)
class_names = dict_characters
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names,title='Confusion matrix')
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names, normalize=True,
title='Normalized confusion matrix')
plot_learning_curve(model, 'Learning Curve For LR Classifier', a, b, (0.85,1.1), 10)
return prediction
# In[62]:
prediction = selectParametersForLR(train_x, train_y, test_x, test_y)
# In[63]:
prediction = selectParametersForSVM(train_x, train_y, test_x, test_y)
x_err_data = pd.DataFrame(columns = train_x.columns)
real_ = test_y.tolist()
indexs = []
err_diag = []
k=0
for i in range(len(prediction)):
if prediction[i] != real_[i]:
x_err_data.loc[k] = test_x.iloc[i].tolist()
indexs.append(test_x.index[i])
err_diag.append(test_y.iloc[i])
k = k + 1
x_err_data.index = indexs
x_err_data["diag"] = err_diag
x_err_data
# In[64]:
data[data['id']==91594602]
# In[65]:
def selectParametersForMLPC(a, b, c, d):
"""http://scikit-learn.org/stable/modules/generated/sklearn.model_selection.GridSearchCV.html
http://scikit-learn.org/stable/modules/grid_search.html#grid-search"""
model = MLPC()
parameters = {'verbose': [False],
'activation': ['logistic', 'relu'],
'max_iter': [1000, 2000], 'learning_rate': ['constant', 'adaptive']}
accuracy_scorer = make_scorer(accuracy_score)
grid_obj = GridSearchCV(model, parameters, scoring=accuracy_scorer)
grid_obj = grid_obj.fit(a, b)
model = grid_obj.best_estimator_
model.fit(a, b)
print('Selected Parameters for Multi-Layer Perceptron NN: ')
print(model)
print('')
kfold = model_selection.KFold(n_splits=10)
accuracy = model_selection.cross_val_score(model, a,b, cv=kfold, scoring='accuracy')
mean = accuracy.mean()
stdev = accuracy.std()
print('SKlearn Multi-Layer Perceptron - Training set accuracy: %s (%s)' % (mean, stdev))
print('')
prediction = model.predict(c)
cnf_matrix = confusion_matrix(d, prediction)
np.set_printoptions(precision=2)
class_names = dict_characters
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names,title='Confusion matrix')
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names, normalize=True,
title='Normalized confusion matrix')
plot_learning_curve(model, 'Learning Curve For MLPC Classifier', a, b, (0.85,1), 10)
# In[66]:
selectParametersForMLPC(train_x, train_y, test_x, test_y)
# In[71]:
def runVotingClassifier(a,b,c,d):
"""http://scikit-learn.org/stable/modules/generated/sklearn.ensemble.VotingClassifier.html
http://scikit-learn.org/stable/modules/ensemble.html#voting-classifier"""
#global votingC, mean, stdev # eventually I should get rid of these global variables and use classes instead. in this case i need these variables for the submission function.
votingC = VotingClassifier(estimators=[('SVM', SVC(C=5.0, cache_size=200, class_weight=None, coef0=0.0,
decision_function_shape='ovr', degree=3, gamma='auto', kernel='rbf',
max_iter=-1, probability=False, random_state=None, shrinking=True,
tol=0.001, verbose=False)), ('LR', LogisticRegression(C=0.1, class_weight=None, dual=False, fit_intercept=True,
intercept_scaling=1, max_iter=100, multi_class='ovr', n_jobs=1,
penalty='l2', random_state=None, solver='liblinear', tol=0.0001,
verbose=0, warm_start=False)),('KNN', KNeighborsClassifier())], voting='hard')
votingC = votingC.fit(a,b)
kfold = model_selection.KFold(n_splits=10)
accuracy = model_selection.cross_val_score(votingC, a,b, cv=kfold, scoring='accuracy')
meanC = accuracy.mean()
stdevC = accuracy.std()
print('Ensemble Voting Classifier - Training set accuracy: %s (%s)' % (meanC, stdevC))
print('')
#return votingC, meanC, stdevC
prediction = votingC.predict(c)
cnf_matrix = confusion_matrix(d, prediction)
np.set_printoptions(precision=2)
class_names = dict_characters
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names,title='Confusion matrix')
plt.figure()
plot_confusion_matrix(cnf_matrix, classes=class_names, normalize=True,
title='Normalized confusion matrix')
plot_learning_curve(votingC, 'Learning Curve For Ensemble Voting Classifier', a, b, (0.85,1), 10)
# In[72]:
runVotingClassifier(train_x, train_y, test_x, test_y)
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