机器学习中的工作流机制
在项目开发的时候,经常需要我们选择使用哪一种模型。同样的数据,可能决策树效果不错,朴素贝叶斯也不错,SVM也挺好。有没有一种方法能够让我们用一份数据,同时训练多个模型,并用某种直观的方式(包括模型得分),观察到模型在既有数据上的效果?有的,管线工作流pipeline就是专门干这个的,再配上决策边界,所有模型只用一眼,就能确定优劣,选择你的梦中情模。上效果图。
分为两行,上面是sklearn自带数据集中的数据,分两类。从第二列开始,每一列是某种模型在当前数据集中的拟合效果。如何查看某种模型效果好坏?从两个方面,左上角的模型得分,和图中颜色深浅,两种颜色的分解代表模型的决策边界。
下面是笔者自己的数据,分为4类。同样不同颜色的分界代表两种类型的判别边界。如果只看模型得分,那得分为100%的模型有5个,选再根据决策边界进一步确定更优秀的模型,为工程所用。这里贴出笔者所用代码供各位修改,也可以直接取官方代码修改
def loadTrainData(): df = pd.read_csv('./your/dataset/path/data.csv') trainDataLabel = df.values nodeData = trainDataLabel[:, :2], trainDataLabel[:, -1] return nodeData def trainAnalySave(): from matplotlib.colors import ListedColormap import joblib from sklearn.datasets import make_circles, make_classification, make_moons from sklearn.discriminant_analysis import QuadraticDiscriminantAnalysis from sklearn.ensemble import AdaBoostClassifier, RandomForestClassifier from sklearn.gaussian_process import GaussianProcessClassifier from sklearn.gaussian_process.kernels import RBF from sklearn.inspection import DecisionBoundaryDisplay from sklearn.model_selection import train_test_split from sklearn.naive_bayes import GaussianNB from sklearn.neighbors import KNeighborsClassifier from sklearn.neural_network import MLPClassifier from sklearn.pipeline import make_pipeline from sklearn.preprocessing import StandardScaler from sklearn.svm import SVC from sklearn.tree import DecisionTreeClassifier names = [ "Nearest Neighbors", "Linear SVM", "RBF SVM", "Gaussian Process", "Decision Tree", "Random Forest", "Neural Net", "AdaBoost", "Naive Bayes", "QDA", ] classifiers = [ KNeighborsClassifier(3), SVC(kernel="linear", C=0.025), SVC(gamma=2, C=1), GaussianProcessClassifier(1.0 * RBF(1.0)), DecisionTreeClassifier(max_depth=5), RandomForestClassifier(max_depth=5, n_estimators=10, max_features=1), MLPClassifier(alpha=1, max_iter=1000), AdaBoostClassifier(), GaussianNB(), QuadraticDiscriminantAnalysis(), ] # X, y = make_classification( # n_features=2, n_redundant=0, n_informative=2, random_state=1, n_clusters_per_class=1 # ) # rng = np.random.RandomState(2) # X += 2 * rng.uniform(size=X.shape) # linearly_separable = (X, y) nodeData = loadTrainData() datasets = [ # make_moons(noise=0.3, random_state=0), make_circles(noise=0.2, factor=0.5, random_state=1), # linearly_separable, nodeData, ] # figure = plt.figure(figsize=(27, 9)) figure = plt.figure(figsize=(15, 4)) i = 1 # iterate over datasets for ds_cnt, ds in enumerate(datasets): # preprocess dataset, split into training and test part X, y = ds X_train, X_test, y_train, y_test = train_test_split( X, y, test_size=0.4, random_state=42 ) x_min, x_max = X[:, 0].min() - 0.5, X[:, 0].max() + 0.5 y_min, y_max = X[:, 1].min() - 0.5, X[:, 1].max() + 0.5 # just plot the dataset first cm = plt.cm.RdBu cm_bright = ListedColormap(["#FF0000", "#00FF00", "#FFFF00", "#0000FF"]) ax = plt.subplot(len(datasets), len(classifiers) + 1, i) if ds_cnt == 0: ax.set_title("Input data") # Plot the training points ax.scatter(X_train[:, 0], X_train[:, 1], c=y_train, cmap=cm_bright, edgecolors="k") # Plot the testing points ax.scatter( X_test[:, 0], X_test[:, 1], c=y_test, cmap=cm_bright, alpha=0.6, edgecolors="k" ) ax.set_xlim(x_min, x_max) ax.set_ylim(y_min, y_max) ax.set_xticks(()) ax.set_yticks(()) i += 1 # iterate over classifiers for name, clf in zip(names, classifiers): ax = plt.subplot(len(datasets), len(classifiers) + 1, i) clf = make_pipeline(StandardScaler(), clf) clf.fit(X_train, y_train) score = clf.score(X_test, y_test) # DecisionBoundaryDisplay.from_estimator( # clf, X, cmap=cm, alpha=0.8, ax=ax, eps=0.5 # ) # save satisfied model savedPath = r'..\models\sklearn\\' savedList = ["Nearest Neighbors", "RBF SVM", "Neural Net"] if name in savedList: joblib.dump(clf, savedPath + name + '.pkl') # Plot the training points ax.scatter( X_train[:, 0], X_train[:, 1], c=y_train, cmap=cm_bright, edgecolors="k" ) # Plot the testing points ax.scatter( X_test[:, 0], X_test[:, 1], c=y_test, cmap=cm_bright, edgecolors="k", alpha=0.6, ) ax.set_xlim(x_min, x_max) ax.set_ylim(y_min, y_max) ax.set_xticks(()) ax.set_yticks(()) if ds_cnt == 0: ax.set_title(name) ax.text( # x_max - 0.3, # y_min + 0.3, x_min + 0.4, y_max - 0.4 - ds_cnt, ("%.2f" % score), # ("%.2f" % score).lstrip("0"), # size=15, size=10, # horizontalalignment="right", horizontalalignment="left", ) i += 1 plt.tight_layout() plt.show() nodeData = loadTrainData() if __name__ == '__main__': trainAnalySave()
注意,这里的DecisionBoundaryDisplay模块,需要安装sklearn的较新版本,因而python也需要较高版本。
最后打个广告,如果有想进修服务器开发相关的技能,这里是可以让你秒变大神的时光隧道。 enjoy~~