我正在尝试使用Scikit-learn进行随机森林回归。使用Pandas加载数据后的第一步是将数据拆分为测试集和训练集。但是,我收到错误:
y中填充最少的类只有1个成员
我搜索了Google,发现了这个错误的各种实例,但我似乎无法理解这个错误的含义。
training_file = "training_data.txt"
data = pd.read_csv(training_file, sep='\t')
y = data.Result
X = data.drop('Result', axis=1)
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=123, stratify=y)
pipeline = make_pipeline(preprocessing.StandardScaler(), RandomForestRegressor(n_estimators=100))
hyperparameters = { 'randomforestregressor__max_features' : ['auto', 'sqrt', 'log2'],
'randomforestregressor__max_depth' : [None, 5, 3, 1] }
model = GridSearchCV(pipeline, hyperparameters, cv=10)
model.fit(X_train, y_train)
prediction = model.predict(X_test)
joblib.dump(model, 'ms5000.pkl')
train_test_split
方法产生此堆栈跟踪:
Traceback (most recent call last):
File "/Users/justin.shapiro/Desktop/IPML_Model/model_definition.py", line 18, in <module>
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.22, random_state=123, stratify=y)
File "/Library/Python/2.7/site-packages/sklearn/model_selection/_split.py", line 1700, in train_test_split
train, test = next(cv.split(X=arrays[0], y=stratify))
File "/Library/Python/2.7/site-packages/sklearn/model_selection/_split.py", line 953, in split
for train, test in self._iter_indices(X, y, groups):
File "/Library/Python/2.7/site-packages/sklearn/model_selection/_split.py", line 1259, in _iter_indices
raise ValueError("The least populated class in y has only 1"
ValueError: The least populated class in y has only 1 member, which is too few. The minimum number of groups for any class cannot be less than 2.
这是我的数据集示例:
var1 var2 var3 var4 var5 var6 var7 var8 Result
high 5000.0 0 60 1000 75 0.23 0.75 17912.0
mid 5000.0 0 60 1000 50 0.23 0.75 18707.0
low 5000.0 0 60 1000 25 0.23 0.75 17912.0
high 5000.0 5 60 1000 75 0.23 0.75 18577.0
mid 5000.0 5 60 1000 50 0.23 0.75 19407.0
low 5000.0 5 60 1000 25 0.23 0.75 18577.0
这是什么错误,如何摆脱它?
答案 0 :(得分:4)
此行引发错误:
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.22, random_state=123, stratify=y)
尝试删除stratify=y