在机器学习中遇到维度问题（Python Scikit）

Question

我对应用机器学习有点陌生，所以我试图教自己如何使用mldata.org和Python scikit包中的任何数据进行线性回归。 我测试了线性回归示例代码（ http://scikit-learn.org/stable/auto_examples/linear_model/plot_ols.html ），并且该代码与糖尿病数据集配合得很好。 但是，我尝试将代码与其他数据集一起使用，例如关于mldata上的地震的代码（ http://mldata.org/repository/data/viewslug/global-earthquakes/ ）。 但是，由于那里的尺寸问题，我无法这样做。

Warning (from warnings module):
  File "/usr/lib/python2.7/dist-packages/numpy/core/_methods.py", line 55
    warnings.warn("Mean of empty slice.", RuntimeWarning)
RuntimeWarning: Mean of empty slice.

Warning (from warnings module):
  File "/usr/lib/python2.7/dist-packages/numpy/core/_methods.py", line 65
    ret, rcount, out=ret, casting='unsafe', subok=False)
RuntimeWarning: invalid value encountered in true_divide

Traceback (most recent call last):
  File "/home/anthony/Documents/Programming/Python/Machine Learning/Scikit/earthquake_linear_regression.py", line 38, in <module>
    regr.fit(earthquake_X_train, earthquake_y_train)
  File "/usr/local/lib/python2.7/dist-packages/sklearn/linear_model/base.py", line 371, in fit
    linalg.lstsq(X, y)
  File "/usr/lib/python2.7/dist-packages/scipy/linalg/basic.py", line 518, in lstsq
    raise ValueError('incompatible dimensions')
ValueError: incompatible dimensions

如何设置数据的维数？

数据大小：

抗震形状（59209，1，4）抗震形状（59189，1）抗震形状（3，59209）抗震形状（3，59209）

编码：

# Code source: Jaques Grobler
# License: BSD 3 clause


import matplotlib.pyplot as plt
import numpy as np
from sklearn import datasets, linear_model
#Experimenting with earthquake data

from sklearn.datasets.mldata import fetch_mldata
import tempfile
test_data_home = tempfile.mkdtemp()


# Load the diabetes dataset
earthquake = fetch_mldata('Global Earthquakes', data_home = test_data_home)


# Use only one feature
earthquake_X = earthquake.data[:, np.newaxis]
earthquake_X_temp = earthquake_X[:, :, 2]

# Split the data into training/testing sets
earthquake_X_train = earthquake_X_temp[:-20]
earthquake_X_test = earthquake_X_temp[-20:]

# Split the targets into training/testing sets
earthquake_y_train = earthquake.target[:-20]
earthquake_y_test = earthquake.target[-20:]
print "Splitting of data for preformance check completed"
# Create linear regression object
regr = linear_model.LinearRegression()
print "Created linear regression object"
# Train the model using the training sets
regr.fit(earthquake_X_train, earthquake_y_train)
print "Dataset trained"
# The coefficients
print('Coefficients: \n', regr.coef_)
# The mean square error
print("Residual sum of squares: %.2f"
      % np.mean((regr.predict(earthquake_X_test) - earthquake_y_test) ** 2))
# Explained variance score: 1 is perfect prediction
print('Variance score: %.2f' % regr.score(earthquake_X_test, earthquake_y_test))

# Plot outputs
plt.scatter(earthquake_X_test, earthquake_y_test,  color='black')
plt.plot(earthquake_X_test, regr.predict(earthquake_X_test), color='blue',
         linewidth=3)

plt.xticks(())
plt.yticks(())

plt.show()

Answer 1

您的目标数组（ earthquake_y_train ）形状错误。 而且实际上它是空的。

当你做

earthquake_y_train = earthquake.target[:-20]

您选择了第一个轴中除最后20个以外的所有行。 并且，根据您发布的数据， earthquake.target (3, 59209)形状为(3, 59209) ，因此没有可供选择的行！

但是，即使有任何错误，仍然会出错。 为什么？ 因为X和y第一个尺寸必须相同。 根据sklearn的文档， LinearRegression的拟合期望X的形状为[n_samples，n_features]和y — [n_samples，n_targets]。

为了修复它，将ys的定义更改为以下内容：

earthquake_y_train = earthquake.target[:, :-20].T
earthquake_y_test = earthquake.target[:, -20:].T

PS即使解决了所有这些问题，脚本中仍然存在一个问题： plt.scatter无法与“多维” ys一起使用。