URLError:

在使用seaborn加载内置数据集时，出现以下错误：

dataset = sns.load_dataset("iris")
dataset.head()

20201010211724175.png

解决方案：
一、原因需要连接外网！ 挂上VPN就解决了。
二、查看源码。

def load_dataset(name, cache=True, data_home=None, **kws):
    """Load an example dataset from the online repository (requires internet).

    This function provides quick access to a small number of example datasets
    that are useful for documenting seaborn or generating reproducible examples
    for bug reports. It is not necessary for normal usage.

    Note that some of the datasets have a small amount of preprocessing applied
    to define a proper ordering for categorical variables.

    Use :func:`get_dataset_names` to see a list of available datasets.

    Parameters
    ----------
    name : str
        Name of the dataset (``{name}.csv`` on
        https://github.com/mwaskom/seaborn-data).
    cache : boolean, optional
        If True, try to load from the local cache first, and save to the cache
        if a download is required.
    data_home : string, optional
        The directory in which to cache data; see :func:`get_data_home`.
    kws : keys and values, optional
        Additional keyword arguments are passed to passed through to
        :func:`pandas.read_csv`.

    Returns
    df : :class:`pandas.DataFrame`
        Tabular data, possibly with some preprocessing applied.

    """
    path = ("https://raw.githubusercontent.com/"
            "mwaskom/seaborn-data/master/{}.csv")
    full_path = path.format(name)

    if cache:
        cache_path = os.path.join(get_data_home(data_home),
                                  os.path.basename(full_path))
        if not os.path.exists(cache_path):
            if name not in get_dataset_names():
                raise ValueError(f"'{name}' is not one of the example datasets.")
            urlretrieve(full_path, cache_path)
        full_path = cache_path
    """

get_data_home()函数

def get_data_home(data_home=None):
    """Return a path to the cache directory for example datasets.

    This directory is then used by :func:`load_dataset`.

    If the ``data_home`` argument is not specified, it tries to read from the
    ``SEABORN_DATA`` environment variable and defaults to ``~/seaborn-data``.

    """
    if data_home is None:
        data_home = os.environ.get('SEABORN_DATA',
                                   os.path.join('~', 'seaborn-data'))
    data_home = os.path.expanduser(data_home)
    if not os.path.exists(data_home):
        os.makedirs(data_home)
    return data_home

def load_dataset(name, cache=True, data_home=None, **kws):

我们会发现，load_dataset()中的几个参数：
name:数据集的名称
cache==True时，
就会根据data_home的值来加载数据集，
此时需要下载seaborn-data数据集到本地（https://github.com/mwaskom/seaborn-data）
然后data_home 设置为seaborn-data的本地路径就可以运行了。

dataset = sns.load_dataset(name="iris",cache=True,data_home="./seaborn-data")
dataset.head()

捕获.PNG

note:当cache为True时，home_data默认路径是 C:\Users