Python scikit-learn 到 JSON

Question

我有一个使用 Python scikit-learn 构建的模型。我知道模型可以以 Pickle 或 Joblib 格式保存。是否有任何现有的方法可以将作业保存为 JSON 格式？请参阅下面的模型构建代码以供参考：

import pandas
from sklearn import model_selection
from sklearn.linear_model import LogisticRegression
import pickle
url = "https://archive.ics.uci.edu/ml/machine-learning-databases/pima-indians-diabetes/pima-indians-diabetes.data"
names =['preg', 'plas', 'pres', 'skin', 'test', 'mass', 'pedi', 'age', 'class']
dataframe = pandas.read_csv(url, names=names)
array = dataframe.values
X = array[:,0:8]
Y = array[:,8]
test_size = 0.33
seed = 7
X_train, X_test, Y_train, Y_test = model_selection.train_test_split(X, Y, test_size=test_size, random_state=seed)
# Fit the model on 33%
model = LogisticRegression()
model.fit(X_train, Y_train)
filename = 'finalized_model.sav'
pickle.dump(model, open(filename, 'wb'))

Answer 1

您必须编写自己的序列化/反序列化配方。幸运的是，逻辑回归基本上可以通过系数和截距来捕捉。但是，LogisticRegression 对象保留了一些其他元数据，我们不妨围绕这些元数据进行捕获。我把下面这些做脏活的函数放在一起。请记住，这仍然很粗糙：

import numpy as np
import json
from sklearn.linear_model import LogisticRegression

def logistic_regression_to_json(lrmodel, file=None):
    if file is not None:
        serialize = lambda x: json.dump(x, file)
    else:
        serialize = json.dumps
    data = {}
    data['init_params'] = lrmodel.get_params()
    data['model_params'] = mp = {}
    for p in ('coef_', 'intercept_','classes_', 'n_iter_'):
        mp[p] = getattr(lrmodel, p).tolist()
    return serialize(data)

def logistic_regression_from_json(jstring):
    data = json.loads(jstring)
    model = LogisticRegression(**data['init_params'])
    for name, p in data['model_params'].items():
        setattr(model, name, np.array(p))
    return model

注意，只需'coef_', 'intercept_','classes_'，您就可以自己进行预测，因为逻辑回归是一个直接的线性模型，它只是矩阵乘法。