.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "auto_examples/tree/plot_tree_regression.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_auto_examples_tree_plot_tree_regression.py>`
        to download the full example code. or to run this example in your browser via Binder

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_auto_examples_tree_plot_tree_regression.py:


===================================================================
决策树回归
===================================================================

使用决策树进行一维回归。

使用 :ref:`决策树 <tree>` 拟合带有噪声观测的正弦曲线。结果是，它学习了近似正弦曲线的局部线性回归。

我们可以看到，如果树的最大深度（由 `max_depth` 参数控制）设置得太高，决策树会学习训练数据的过细细节并从噪声中学习，即它们会过拟合。

.. GENERATED FROM PYTHON SOURCE LINES 12-46



.. image-sg:: /auto_examples/tree/images/sphx_glr_plot_tree_regression_001.png
   :alt: Decision Tree Regression
   :srcset: /auto_examples/tree/images/sphx_glr_plot_tree_regression_001.png
   :class: sphx-glr-single-img





.. code-block:: Python


    # 导入必要的模块和库
    import matplotlib.pyplot as plt
    import numpy as np

    from sklearn.tree import DecisionTreeRegressor

    # 创建一个随机数据集
    rng = np.random.RandomState(1)
    X = np.sort(5 * rng.rand(80, 1), axis=0)
    y = np.sin(X).ravel()
    y[::5] += 3 * (0.5 - rng.rand(16))

    # 拟合回归模型
    regr_1 = DecisionTreeRegressor(max_depth=2)
    regr_2 = DecisionTreeRegressor(max_depth=5)
    regr_1.fit(X, y)
    regr_2.fit(X, y)

    # Predict
    X_test = np.arange(0.0, 5.0, 0.01)[:, np.newaxis]
    y_1 = regr_1.predict(X_test)
    y_2 = regr_2.predict(X_test)

    # Plot the results
    plt.figure()
    plt.scatter(X, y, s=20, edgecolor="black", c="darkorange", label="data")
    plt.plot(X_test, y_1, color="cornflowerblue", label="max_depth=2", linewidth=2)
    plt.plot(X_test, y_2, color="yellowgreen", label="max_depth=5", linewidth=2)
    plt.xlabel("data")
    plt.ylabel("target")
    plt.title("Decision Tree Regression")
    plt.legend()
    plt.show()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.039 seconds)


.. _sphx_glr_download_auto_examples_tree_plot_tree_regression.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: binder-badge

      .. image:: images/binder_badge_logo.svg
        :target: https://mybinder.org/v2/gh/scikit-learn/scikit-learn/main?urlpath=lab/tree/notebooks/auto_examples/tree/plot_tree_regression.ipynb
        :alt: Launch binder
        :width: 150 px

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: plot_tree_regression.ipynb <plot_tree_regression.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: plot_tree_regression.py <plot_tree_regression.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: plot_tree_regression.zip <plot_tree_regression.zip>`


.. include:: plot_tree_regression.recommendations


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_