机器学习基础04DAY

scikit-learn数据集

我们将介绍sklearn中的数据集类，模块包括用于加载数据集的实用程序，包括加载和获取流行参考数据集的方法。它还具有一些人工数据生成器。

sklearn.datasets

（1）datasets.load_*()

获取小规模数据集，数据包含在datasets里

（2）datasets.fetch_*()

获取大规模数据集，需要从网络上下载，函数的第一个参数是data_home，表示数据集下载的目录，默认是 ~/scikit_learn_data/，要修改默认目录，可以修改环境变量SCIKIT_LEARN_DATA

（3）datasets.make_*()

本地生成数据集

load*和 fetch* 函数返回的数据类型是 datasets.base.Bunch，本质上是一个 dict，它的键值对可用通过对象的属性方式访问。主要包含以下属性：

• data：特征数据数组，是 n_samples * n_features 的二维 numpy.ndarray 数组
• target：标签数组，是 n_samples 的一维 numpy.ndarray 数组
• DESCR：数据描述
• feature_names：特征名
• target_names：标签名

数据集目录可以通过datasets.get_data_home()获取，clear_data_home(data_home=None)删除所有下载数据

• datasets.get_data_home(data_home=None)

返回scikit学习数据目录的路径。这个文件夹被一些大的数据集装载器使用，以避免下载数据。默认情况下，数据目录设置为用户主文件夹中名为“scikit_learn_data”的文件夹。或者，可以通过“SCIKIT_LEARN_DATA”环境变量或通过给出显式的文件夹路径以编程方式设置它。'〜'符号扩展到用户主文件夹。如果文件夹不存在，则会自动创建。

• sklearn.datasets.clear_data_home(data_home=None)

删除存储目录中的数据

获取小数据集

用于分类

• sklearn.datasets.load_iris

class sklearn.datasets.load_iris(return_X_y=False)
  """
  加载并返回虹膜数据集

  :param return_X_y: 如果为True，则返回而不是Bunch对象，默认为False

  :return: Bunch对象，如果return_X_y为True，那么返回tuple，（data,target）
  """
In [12]: from sklearn.datasets import load_iris
    ...: data = load_iris()
    ...:

In [13]: data.target
Out[13]:
array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2])

In [14]: data.feature_names
Out[14]:
['sepal length (cm)',
 'sepal width (cm)',
 'petal length (cm)',
 'petal width (cm)']

In [15]: data.target_names
Out[15]:
array(['setosa', 'versicolor', 'virginica'],
      dtype='|S10')

In [17]: data.target[[1,10, 100]]
Out[17]: array([0, 0, 2])

名称	数量
类别	3
特征	4
样本数量	150
每个类别数量	50

• sklearn.datasets.load_digits

class sklearn.datasets.load_digits(n_class=10, return_X_y=False)
    """
    加载并返回数字数据集

    :param n_class: 整数，介于0和10之间，可选（默认= 10，要返回的类的数量

    :param return_X_y: 如果为True，则返回而不是Bunch对象，默认为False

    :return: Bunch对象，如果return_X_y为True，那么返回tuple，（data,target）
    """
In [20]: from sklearn.datasets import load_digits

In [21]: digits = load_digits()

In [22]: print(digits.data.shape)
(1797, 64)

In [23]: digits.target
Out[23]: array([0, 1, 2, ..., 8, 9, 8])

In [24]: digits.target_names
Out[24]: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

In [25]: digits.images
Out[25]:
array([[[  0.,   0.,   5., ...,   1.,   0.,   0.],
        [  0.,   0.,  13., ...,  15.,   5.,   0.],
        [  0.,   3.,  15., ...,  11.,   8.,   0.],
        ...,
        [  0.,   4.,  11., ...,  12.,   7.,   0.],
        [  0.,   2.,  14., ...,  12.,   0.,   0.],
        [  0.,   0.,   6., ...,   0.,   0.,   0.]],

        [[  0.,   0.,  10., ...,   1.,   0.,   0.],
        [  0.,   2.,  16., ...,   1.,   0.,   0.],
        [  0.,   0.,  15., ...,  15.,   0.,   0.],
        ...,
        [  0.,   4.,  16., ...,  16.,   6.,   0.],
        [  0.,   8.,  16., ...,  16.,   8.,   0.],
        [  0.,   1.,   8., ...,  12.,   1.,   0.]]])

名称	数量
类别	10
特征	64
样本数量	1797

用于回归

• sklearn.datasets.load_boston

class  sklearn.datasets.load_boston(return_X_y=False)
  """
  加载并返回波士顿房价数据集

  :param return_X_y: 如果为True，则返回而不是Bunch对象，默认为False

  :return: Bunch对象，如果return_X_y为True，那么返回tuple，（data,target）
  """
In [34]: from sklearn.datasets import load_boston

In [35]: boston = load_boston()

In [36]: boston.data.shape
Out[36]: (506, 13)

In [37]: boston.feature_names
Out[37]:
array(['CRIM', 'ZN', 'INDUS', 'CHAS', 'NOX', 'RM', 'AGE', 'DIS', 'RAD',
       'TAX', 'PTRATIO', 'B', 'LSTAT'],
      dtype='|S7')

In [38]:

名称	数量
目标类别	5-50
特征	13
样本数量	506

• sklearn.datasets.load_diabetes

class sklearn.datasets.load_diabetes(return_X_y=False)
  """
  加载和返回糖尿病数据集

  :param return_X_y: 如果为True，则返回而不是Bunch对象，默认为False

  :return: Bunch对象，如果return_X_y为True，那么返回tuple，（data,target）
  """
In [13]:  from sklearn.datasets import load_diabetes

In [14]: diabetes = load_diabetes()

In [15]: diabetes.data
Out[15]:
array([[ 0.03807591,  0.05068012,  0.06169621, ..., -0.00259226,
         0.01990842, -0.01764613],
       [-0.00188202, -0.04464164, -0.05147406, ..., -0.03949338,
        -0.06832974, -0.09220405],
       [ 0.08529891,  0.05068012,  0.04445121, ..., -0.00259226,
         0.00286377, -0.02593034],
       ...,
       [ 0.04170844,  0.05068012, -0.01590626, ..., -0.01107952,
        -0.04687948,  0.01549073],
       [-0.04547248, -0.04464164,  0.03906215, ...,  0.02655962,
         0.04452837, -0.02593034],
       [-0.04547248, -0.04464164, -0.0730303 , ..., -0.03949338,
        -0.00421986,  0.00306441]])

名称	数量
目标范围	25-346
特征	10
样本数量	442

获取大数据集

• sklearn.datasets.fetch_20newsgroups

class sklearn.datasets.fetch_20newsgroups(data_home=None, subset='train', categories=None, shuffle=True, random_state=42, remove=(), download_if_missing=True)
  """
  加载20个新闻组数据集中的文件名和数据

  :param subset: 'train'或者'test','all'，可选，选择要加载的数据集：训练集的“训练”，测试集的“测试”，两者的“全部”，具有洗牌顺序

  :param data_home: 可选，默认值：无，指定数据集的下载和缓存文件夹。如果没有，所有scikit学习数据都存储在'〜/ scikit_learn_data'子文件夹中

  :param categories: 无或字符串或Unicode的集合，如果没有（默认），加载所有类别。如果不是无，要加载的类别名称列表（忽略其他类别）

  :param shuffle: 是否对数据进行洗牌

  :param random_state: numpy随机数生成器或种子整数

  :param download_if_missing: 可选，默认为True，如果False，如果数据不在本地可用而不是尝试从源站点下载数据，则引发IOError

  :param remove: 元组
  """
In [29]: from sklearn.datasets import fetch_20newsgroups

In [30]: data_test = fetch_20newsgroups(subset='test',shuffle=True, random_sta
    ...: te=42)

In [31]: data_train = fetch_20newsgroups(subset='train',shuffle=True, random_s
    ...: tate=42)

• sklearn.datasets.fetch_20newsgroups_vectorized

class sklearn.datasets.fetch_20newsgroups_vectorized(subset='train', remove=(), data_home=None)
  """
  加载20个新闻组数据集并将其转换为tf-idf向量，这是一个方便的功能; 使用sklearn.feature_extraction.text.Vectorizer的默认设置完成tf-idf 转换。对于更高级的使用（停止词过滤，n-gram提取等），将fetch_20newsgroup与自定义Vectorizer或CountVectorizer组合在一起

  :param subset: 'train'或者'test','all'，可选，选择要加载的数据集：训练集的“训练”，测试集的“测试”，两者的“全部”，具有洗牌顺序

  :param data_home: 可选，默认值：无，指定数据集的下载和缓存文件夹。如果没有，所有scikit学习数据都存储在'〜/ scikit_learn_data'子文件夹中

  :param remove: 元组
  """
In [57]: from sklearn.datasets import fetch_20newsgroups_vectorized

In [58]: bunch = fetch_20newsgroups_vectorized(subset='all')

In [59]: from sklearn.utils import shuffle

In [60]: X, y = shuffle(bunch.data, bunch.target)
    ...: offset = int(X.shape[0] * 0.8)
    ...: X_train, y_train = X[:offset], y[:offset]
    ...: X_test, y_test = X[offset:], y[offset:]
    ...:

获取本地生成数据

生成本地分类数据：

• sklearn.datasets.make_classification

  class make_classification(n_samples=100, n_features=20, n_informative=2, n_redundant=2, n_repeated=0, n_classes=2, n_clusters_per_class=2, weights=None, flip_y=0.01, class_sep=1.0, hypercube=True, shift=0.0, scale=1.0, shuffle=True, random_state=None)
  """
  生成用于分类的数据集
  
  :param n_samples:int，optional（default = 100)，样本数量
  
  :param n_features:int，可选（默认= 20），特征总数
  
  :param n_classes:int，可选（default = 2),类（或标签）的分类问题的数量
  
  :param random_state:int，RandomState实例或无，可选（默认=无）
    如果int，random_state是随机数生成器使用的种子; 如果RandomState的实例，random_state是随机数生成器; 如果没有，随机数生成器所使用的RandomState实例np.random
  
  :return :X,特征数据集；y,目标分类值
  """
  

from sklearn.datasets.samples_generator import make_classification
X,y= datasets.make_classification(n_samples=100000, n_features=20,n_informative=2, n_redundant=10,random_state=42)

生成本地回归数据：

• sklearn.datasets.make_regression

class make_regression(n_samples=100, n_features=100, n_informative=10, n_targets=1, bias=0.0, effective_rank=None, tail_strength=0.5, noise=0.0, shuffle=True, coef=False, random_state=None)
  """
  生成用于回归的数据集

  :param n_samples:int，optional（default = 100)，样本数量

  :param  n_features:int,optional（default = 100)，特征数量

  :param  coef:boolean，optional（default = False），如果为True，则返回底层线性模型的系数

  :param random_state:int，RandomState实例或无，可选（默认=无）
    如果int，random_state是随机数生成器使用的种子; 如果RandomState的实例，random_state是随机数生成器; 如果没有，随机数生成器所使用的RandomState实例np.random

  :return :X,特征数据集；y,目标值
  """
from sklearn.datasets.samples_generator import make_regression
X, y = make_regression(n_samples=200, n_features=5000, random_state=42)

数据的分类与划分

数据集返回的类型

• load和fetch返回的数据类型datasets.base.Bunch（字典格式）
• data: 特征数据数组，是[n_samples * n_features]的二维numpy.ndarray数组
• target:标签数组，是n_samples的一维numpy.ndarray数组
• DESCR:数据描述
• feature_names: 特征名,新闻数据，手写数字、回归数据集没有
• target_names:标签名,回归数据集没有

分类数据集

鸢尾花数据集

In [ ]:

from sklearn.datasets import load_iris

# 实例化数据集
iris = load_iris()

#查看特征值
iris.data

Out[ ]:

array([[5.1, 3.5, 1.4, 0.2],
       [4.9, 3. , 1.4, 0.2],
       [4.7, 3.2, 1.3, 0.2],
       [4.6, 3.1, 1.5, 0.2],
       [5. , 3.6, 1.4, 0.2],
       [5.4, 3.9, 1.7, 0.4],
       [4.6, 3.4, 1.4, 0.3],
       [5. , 3.4, 1.5, 0.2],
       [4.4, 2.9, 1.4, 0.2],
       [4.9, 3.1, 1.5, 0.1],
       [5.4, 3.7, 1.5, 0.2],
       [4.8, 3.4, 1.6, 0.2],
       [4.8, 3. , 1.4, 0.1],
       [4.3, 3. , 1.1, 0.1],
       [5.8, 4. , 1.2, 0.2],
       [5.7, 4.4, 1.5, 0.4],
       [5.4, 3.9, 1.3, 0.4],
       [5.1, 3.5, 1.4, 0.3],
       [5.7, 3.8, 1.7, 0.3],
       [5.1, 3.8, 1.5, 0.3],
       [5.4, 3.4, 1.7, 0.2],
       [5.1, 3.7, 1.5, 0.4],
       [4.6, 3.6, 1. , 0.2],
       [5.1, 3.3, 1.7, 0.5],
       [4.8, 3.4, 1.9, 0.2],
       [5. , 3. , 1.6, 0.2],
       [5. , 3.4, 1.6, 0.4],
       [5.2, 3.5, 1.5, 0.2],
       [5.2, 3.4, 1.4, 0.2],
       [4.7, 3.2, 1.6, 0.2],
       [4.8, 3.1, 1.6, 0.2],
       [5.4, 3.4, 1.5, 0.4],
       [5.2, 4.1, 1.5, 0.1],
       [5.5, 4.2, 1.4, 0.2],
       [4.9, 3.1, 1.5, 0.2],
       [5. , 3.2, 1.2, 0.2],
       [5.5, 3.5, 1.3, 0.2],
       [4.9, 3.6, 1.4, 0.1],
       [4.4, 3. , 1.3, 0.2],
       [5.1, 3.4, 1.5, 0.2],
       [5. , 3.5, 1.3, 0.3],
       [4.5, 2.3, 1.3, 0.3],
       [4.4, 3.2, 1.3, 0.2],
       [5. , 3.5, 1.6, 0.6],
       [5.1, 3.8, 1.9, 0.4],
       [4.8, 3. , 1.4, 0.3],
       [5.1, 3.8, 1.6, 0.2],
       [4.6, 3.2, 1.4, 0.2],
       [5.3, 3.7, 1.5, 0.2],
       [5. , 3.3, 1.4, 0.2],
       [7. , 3.2, 4.7, 1.4],
       [6.4, 3.2, 4.5, 1.5],
       [6.9, 3.1, 4.9, 1.5],
       [5.5, 2.3, 4. , 1.3],
       [6.5, 2.8, 4.6, 1.5],
       [5.7, 2.8, 4.5, 1.3],
       [6.3, 3.3, 4.7, 1.6],
       [4.9, 2.4, 3.3, 1. ],
       [6.6, 2.9, 4.6, 1.3],
       [5.2, 2.7, 3.9, 1.4],
       [5. , 2. , 3.5, 1. ],
       [5.9, 3. , 4.2, 1.5],
       [6. , 2.2, 4. , 1. ],
       [6.1, 2.9, 4.7, 1.4],
       [5.6, 2.9, 3.6, 1.3],
       [6.7, 3.1, 4.4, 1.4],
       [5.6, 3. , 4.5, 1.5],
       [5.8, 2.7, 4.1, 1. ],
       [6.2, 2.2, 4.5, 1.5],
       [5.6, 2.5, 3.9, 1.1],
       [5.9, 3.2, 4.8, 1.8],
       [6.1, 2.8, 4. , 1.3],
       [6.3, 2.5, 4.9, 1.5],
       [6.1, 2.8, 4.7, 1.2],
       [6.4, 2.9, 4.3, 1.3],
       [6.6, 3. , 4.4, 1.4],
       [6.8, 2.8, 4.8, 1.4],
       [6.7, 3. , 5. , 1.7],
       [6. , 2.9, 4.5, 1.5],
       [5.7, 2.6, 3.5, 1. ],
       [5.5, 2.4, 3.8, 1.1],
       [5.5, 2.4, 3.7, 1. ],
       [5.8, 2.7, 3.9, 1.2],
       [6. , 2.7, 5.1, 1.6],
       [5.4, 3. , 4.5, 1.5],
       [6. , 3.4, 4.5, 1.6],
       [6.7, 3.1, 4.7, 1.5],
       [6.3, 2.3, 4.4, 1.3],
       [5.6, 3. , 4.1, 1.3],
       [5.5, 2.5, 4. , 1.3],
       [5.5, 2.6, 4.4, 1.2],
       [6.1, 3. , 4.6, 1.4],
       [5.8, 2.6, 4. , 1.2],
       [5. , 2.3, 3.3, 1. ],
       [5.6, 2.7, 4.2, 1.3],
       [5.7, 3. , 4.2, 1.2],
       [5.7, 2.9, 4.2, 1.3],
       [6.2, 2.9, 4.3, 1.3],
       [5.1, 2.5, 3. , 1.1],
       [5.7, 2.8, 4.1, 1.3],
       [6.3, 3.3, 6. , 2.5],
       [5.8, 2.7, 5.1, 1.9],
       [7.1, 3. , 5.9, 2.1],
       [6.3, 2.9, 5.6, 1.8],
       [6.5, 3. , 5.8, 2.2],
       [7.6, 3. , 6.6, 2.1],
       [4.9, 2.5, 4.5, 1.7],
       [7.3, 2.9, 6.3, 1.8],
       [6.7, 2.5, 5.8, 1.8],
       [7.2, 3.6, 6.1, 2.5],
       [6.5, 3.2, 5.1, 2. ],
       [6.4, 2.7, 5.3, 1.9],
       [6.8, 3. , 5.5, 2.1],
       [5.7, 2.5, 5. , 2. ],
       [5.8, 2.8, 5.1, 2.4],
       [6.4, 3.2, 5.3, 2.3],
       [6.5, 3. , 5.5, 1.8],
       [7.7, 3.8, 6.7, 2.2],
       [7.7, 2.6, 6.9, 2.3],
       [6. , 2.2, 5. , 1.5],
       [6.9, 3.2, 5.7, 2.3],
       [5.6, 2.8, 4.9, 2. ],
       [7.7, 2.8, 6.7, 2. ],
       [6.3, 2.7, 4.9, 1.8],
       [6.7, 3.3, 5.7, 2.1],
       [7.2, 3.2, 6. , 1.8],
       [6.2, 2.8, 4.8, 1.8],
       [6.1, 3. , 4.9, 1.8],
       [6.4, 2.8, 5.6, 2.1],
       [7.2, 3. , 5.8, 1.6],
       [7.4, 2.8, 6.1, 1.9],
       [7.9, 3.8, 6.4, 2. ],
       [6.4, 2.8, 5.6, 2.2],
       [6.3, 2.8, 5.1, 1.5],
       [6.1, 2.6, 5.6, 1.4],
       [7.7, 3. , 6.1, 2.3],
       [6.3, 3.4, 5.6, 2.4],
       [6.4, 3.1, 5.5, 1.8],
       [6. , 3. , 4.8, 1.8],
       [6.9, 3.1, 5.4, 2.1],
       [6.7, 3.1, 5.6, 2.4],
       [6.9, 3.1, 5.1, 2.3],
       [5.8, 2.7, 5.1, 1.9],
       [6.8, 3.2, 5.9, 2.3],
       [6.7, 3.3, 5.7, 2.5],
       [6.7, 3. , 5.2, 2.3],
       [6.3, 2.5, 5. , 1.9],
       [6.5, 3. , 5.2, 2. ],
       [6.2, 3.4, 5.4, 2.3],
       [5.9, 3. , 5.1, 1.8]])

In [ ]:

#查看数据形状
iris.data.shape
# 4个特征，150个样本

Out[ ]:

(150, 4)

In [ ]:

# 查看标签数组
iris.target

Out[ ]:

array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
       1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
       2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2])

In [ ]:

# 查看数据的描述
print(iris.DESCR)
.. _iris_dataset:

Iris plants dataset
--------------------

**Data Set Characteristics:**

    :Number of Instances: 150 (50 in each of three classes)
    :Number of Attributes: 4 numeric, predictive attributes and the class
    :Attribute Information:
        - sepal length in cm
        - sepal width in cm
        - petal length in cm
        - petal width in cm
        - class:
                - Iris-Setosa
                - Iris-Versicolour
                - Iris-Virginica

    :Summary Statistics:

    ============== ==== ==== ======= ===== ====================
                    Min  Max   Mean    SD   Class Correlation
    ============== ==== ==== ======= ===== ====================
    sepal length:   4.3  7.9   5.84   0.83    0.7826
    sepal width:    2.0  4.4   3.05   0.43   -0.4194
    petal length:   1.0  6.9   3.76   1.76    0.9490  (high!)
    petal width:    0.1  2.5   1.20   0.76    0.9565  (high!)
    ============== ==== ==== ======= ===== ====================

    :Missing Attribute Values: None
    :Class Distribution: 33.3% for each of 3 classes.
    :Creator: R.A. Fisher
    :Donor: Michael Marshall (MARSHALL%PLU@io.arc.nasa.gov)
    :Date: July, 1988

The famous Iris database, first used by Sir R.A. Fisher. The dataset is taken
from Fisher's paper. Note that it's the same as in R, but not as in the UCI
Machine Learning Repository, which has two wrong data points.

This is perhaps the best known database to be found in the
pattern recognition literature.  Fisher's paper is a classic in the field and
is referenced frequently to this day.  (See Duda & Hart, for example.)  The
data set contains 3 classes of 50 instances each, where each class refers to a
type of iris plant.  One class is linearly separable from the other 2; the
latter are NOT linearly separable from each other.

.. topic:: References

   - Fisher, R.A. "The use of multiple measurements in taxonomic problems"
     Annual Eugenics, 7, Part II, 179-188 (1936); also in "Contributions to
     Mathematical Statistics" (John Wiley, NY, 1950).
   - Duda, R.O., & Hart, P.E. (1973) Pattern Classification and Scene Analysis.
     (Q327.D83) John Wiley & Sons.  ISBN 0-471-22361-1.  See page 218.
   - Dasarathy, B.V. (1980) "Nosing Around the Neighborhood: A New System
     Structure and Classification Rule for Recognition in Partially Exposed
     Environments".  IEEE Transactions on Pattern Analysis and Machine
     Intelligence, Vol. PAMI-2, No. 1, 67-71.
   - Gates, G.W. (1972) "The Reduced Nearest Neighbor Rule".  IEEE Transactions
     on Information Theory, May 1972, 431-433.
   - See also: 1988 MLC Proceedings, 54-64.  Cheeseman et al"s AUTOCLASS II
     conceptual clustering system finds 3 classes in the data.
   - Many, many more ...

In [ ]:

# 查看特征名
iris.feature_names

Out[ ]:

['sepal length (cm)',
 'sepal width (cm)',
 'petal length (cm)',
 'petal width (cm)']

In [ ]:

# 查看目标名
iris.target_names

Out[ ]:

array(['setosa', 'versicolor', 'virginica'], dtype='<U10')

回归数据集

糖尿病数据集

In [ ]:

from sklearn.datasets import load_diabetes

#实例化
diabetes = load_diabetes()
print(diabetes.DESCR)
.. _diabetes_dataset:

Diabetes dataset
----------------

Ten baseline variables, age, sex, body mass index, average blood
pressure, and six blood serum measurements were obtained for each of n =
442 diabetes patients, as well as the response of interest, a
quantitative measure of disease progression one year after baseline.

**Data Set Characteristics:**

  :Number of Instances: 442

  :Number of Attributes: First 10 columns are numeric predictive values

  :Target: Column 11 is a quantitative measure of disease progression one year after baseline

  :Attribute Information:
      - age     age in years
      - sex
      - bmi     body mass index
      - bp      average blood pressure
      - s1      tc, total serum cholesterol
      - s2      ldl, low-density lipoproteins
      - s3      hdl, high-density lipoproteins
      - s4      tch, total cholesterol / HDL
      - s5      ltg, possibly log of serum triglycerides level
      - s6      glu, blood sugar level

Note: Each of these 10 feature variables have been mean centered and scaled by the standard deviation times the square root of `n_samples` (i.e. the sum of squares of each column totals 1).

Source URL:
https://www4.stat.ncsu.edu/~boos/var.select/diabetes.html

For more information see:
Bradley Efron, Trevor Hastie, Iain Johnstone and Robert Tibshirani (2004) "Least Angle Regression," Annals of Statistics (with discussion), 407-499.
(https://web.stanford.edu/~hastie/Papers/LARS/LeastAngle_2002.pdf)

In [ ]:

diabetes.data

Out[ ]:

array([[ 0.03807591,  0.05068012,  0.06169621, ..., -0.00259226,
         0.01990749, -0.01764613],
       [-0.00188202, -0.04464164, -0.05147406, ..., -0.03949338,
        -0.06833155, -0.09220405],
       [ 0.08529891,  0.05068012,  0.04445121, ..., -0.00259226,
         0.00286131, -0.02593034],
       ...,
       [ 0.04170844,  0.05068012, -0.01590626, ..., -0.01107952,
        -0.04688253,  0.01549073],
       [-0.04547248, -0.04464164,  0.03906215, ...,  0.02655962,
         0.04452873, -0.02593034],
       [-0.04547248, -0.04464164, -0.0730303 , ..., -0.03949338,
        -0.00422151,  0.00306441]])

In [ ]:

diabetes.target

Out[ ]:

array([151.,  75., 141., 206., 135.,  97., 138.,  63., 110., 310., 101.,
        69., 179., 185., 118., 171., 166., 144.,  97., 168.,  68.,  49.,
        68., 245., 184., 202., 137.,  85., 131., 283., 129.,  59., 341.,
        87.,  65., 102., 265., 276., 252.,  90., 100.,  55.,  61.,  92.,
       259.,  53., 190., 142.,  75., 142., 155., 225.,  59., 104., 182.,
       128.,  52.,  37., 170., 170.,  61., 144.,  52., 128.,  71., 163.,
       150.,  97., 160., 178.,  48., 270., 202., 111.,  85.,  42., 170.,
       200., 252., 113., 143.,  51.,  52., 210.,  65., 141.,  55., 134.,
        42., 111.,  98., 164.,  48.,  96.,  90., 162., 150., 279.,  92.,
        83., 128., 102., 302., 198.,  95.,  53., 134., 144., 232.,  81.,
       104.,  59., 246., 297., 258., 229., 275., 281., 179., 200., 200.,
       173., 180.,  84., 121., 161.,  99., 109., 115., 268., 274., 158.,
       107.,  83., 103., 272.,  85., 280., 336., 281., 118., 317., 235.,
        60., 174., 259., 178., 128.,  96., 126., 288.,  88., 292.,  71.,
       197., 186.,  25.,  84.,  96., 195.,  53., 217., 172., 131., 214.,
        59.,  70., 220., 268., 152.,  47.,  74., 295., 101., 151., 127.,
       237., 225.,  81., 151., 107.,  64., 138., 185., 265., 101., 137.,
       143., 141.,  79., 292., 178.,  91., 116.,  86., 122.,  72., 129.,
       142.,  90., 158.,  39., 196., 222., 277.,  99., 196., 202., 155.,
        77., 191.,  70.,  73.,  49.,  65., 263., 248., 296., 214., 185.,
        78.,  93., 252., 150.,  77., 208.,  77., 108., 160.,  53., 220.,
       154., 259.,  90., 246., 124.,  67.,  72., 257., 262., 275., 177.,
        71.,  47., 187., 125.,  78.,  51., 258., 215., 303., 243.,  91.,
       150., 310., 153., 346.,  63.,  89.,  50.,  39., 103., 308., 116.,
       145.,  74.,  45., 115., 264.,  87., 202., 127., 182., 241.,  66.,
        94., 283.,  64., 102., 200., 265.,  94., 230., 181., 156., 233.,
        60., 219.,  80.,  68., 332., 248.,  84., 200.,  55.,  85.,  89.,
        31., 129.,  83., 275.,  65., 198., 236., 253., 124.,  44., 172.,
       114., 142., 109., 180., 144., 163., 147.,  97., 220., 190., 109.,
       191., 122., 230., 242., 248., 249., 192., 131., 237.,  78., 135.,
       244., 199., 270., 164.,  72.,  96., 306.,  91., 214.,  95., 216.,
       263., 178., 113., 200., 139., 139.,  88., 148.,  88., 243.,  71.,
        77., 109., 272.,  60.,  54., 221.,  90., 311., 281., 182., 321.,
        58., 262., 206., 233., 242., 123., 167.,  63., 197.,  71., 168.,
       140., 217., 121., 235., 245.,  40.,  52., 104., 132.,  88.,  69.,
       219.,  72., 201., 110.,  51., 277.,  63., 118.,  69., 273., 258.,
        43., 198., 242., 232., 175.,  93., 168., 275., 293., 281.,  72.,
       140., 189., 181., 209., 136., 261., 113., 131., 174., 257.,  55.,
        84.,  42., 146., 212., 233.,  91., 111., 152., 120.,  67., 310.,
        94., 183.,  66., 173.,  72.,  49.,  64.,  48., 178., 104., 132.,
       220.,  57.])

In [ ]:

print("糖尿病数据集的特征名：{0}\n糖尿病数据集的目标值文件名：{1}".format(diabetes.feature_names, diabetes.target_filename))
糖尿病数据集的特征名：['age', 'sex', 'bmi', 'bp', 's1', 's2', 's3', 's4', 's5', 's6']
糖尿病数据集的目标值文件名：diabetes_target.csv.gz

数据集分割（训练集与测试集）

In [ ]:

from sklearn.model_selection import train_test_split

x_train, x_test, y_train, y_test = train_test_split(diabetes.data, diabetes.target, test_size=0.25)

Out[ ]:

(111,)