此代码产生错误:
IndexError: invalid index to scalar variable.
在该行: results.append(RMSPE(np.expm1(y_train[testcv]), [y[1] for y in y_test]))
如何解决?
import pandas as pd
import numpy as np
from sklearn import ensemble
from sklearn import cross_validation
def ToWeight(y):
w = np.zeros(y.shape, dtype=float)
ind = y != 0
w[ind] = 1./(y[ind]**2)
return w
def RMSPE(y, yhat):
w = ToWeight(y)
rmspe = np.sqrt(np.mean( w * (y - yhat)**2 ))
return rmspe
forest = ensemble.RandomForestRegressor(n_estimators=10, min_samples_split=2, n_jobs=-1)
print ("Cross validations")
cv = cross_validation.KFold(len(train), n_folds=5)
results = []
for traincv, testcv in cv:
y_test = np.expm1(forest.fit(X_train[traincv], y_train[traincv]).predict(X_train[testcv]))
results.append(RMSPE(np.expm1(y_train[testcv]), [y[1] for y in y_test]))
testcv
是:
[False False False ..., True True True]
原文由 Klausos Klausos 发布,翻译遵循 CC BY-SA 4.0 许可协议
您正在尝试索引标量(不可迭代)值:
当您调用
[y for y in test]
时,您已经迭代了这些值,因此您在y
中获得了一个值。您的代码与尝试执行以下操作相同:
我不确定您要将什么放入结果数组,但您需要摆脱
[y[1] for y in y_test]
。如果您想将 y_test 中的每个 y 附加到结果,您需要将列表理解进一步扩展到如下所示:
或者只使用 for 循环: