PolynomialFeatures fit_transform 给出值错误答案

【问题标题】：PolynomialFeatures fit_transform is giving Value errorPolynomialFeatures fit_transform 给出值错误
【发布时间】：2014-12-14 22:24:33
【问题描述】：

我在尝试运行多项式回归示例时遇到 ValueError：

from sklearn.preprocessing import PolynomialFeatures
import numpy as np

poly = PolynomialFeatures(degree=2)
poly.fit_transform(X)   ==> ERROR

错误是：

File "/root/.local/lib/python2.7/site-packages/sklearn/base.py", line 426, in fit_transform
    return self.fit(X, **fit_params).transform(X)

File "/root/.local/lib/python2.7/site-packages/sklearn/preprocessing/data.py", line 473, in fit
  self.include_bias)

File "/root/.local/lib/python2.7/site-packages/sklearn/preprocessing/data.py", line 463, in _power_matrix
  powers = np.vstack(np.bincount(c, minlength=n_features) for c in combn)

File "/usr/lib/python2.7/dist-packages/numpy/core/shape_base.py", line 226, in vstack
  return _nx.concatenate(map(atleast_2d,tup),0)

File "/root/.local/lib/python2.7/site-packages/sklearn/preprocessing/data.py", line 463, in <genexpr>

  powers = np.vstack(np.bincount(c, minlength=n_features) for c in combn)  
  ValueError: The first argument cannot be empty.

我的 scikit-learn 版本是 0.15.2

此示例来自：http://scikit-learn.org/stable/modules/linear_model.html#polynomial-regression-extending-linear-models-with-basis-functions

【问题讨论】：

>>> X.shape (3, 2) 即使在这个例子中也会发生这种情况：scikit-learn.org/stable/modules/…
您能告诉我您使用的是哪个 NumPy 版本吗？我无法在本地重现此内容。

标签： python numpy scikit-learn scipy

【解决方案1】：

在创建这样的 PolynomialFeatures 类的对象时，您应该尝试将 include_bias 设置为 False

poly = PolynomialFeatures(degree=2, include_bias=False)

请注意，示例中的最终矩阵现在没有第一列。

【讨论】：