python 未解之谜

本人的  python  numpy ...安装应该是没有问题的   但是运行《机器学习系统设计》源代码  却出了问题 

源码如下 ：

from sklearn.datasets import load_iris
import numpy as np

data = load_iris()
features = data['data']
labels = data['target_names'][data['target']]

plength = features[:,2]
is_setosa = (labels == 'setosa')

print('Maximum of setosa: {0}.'.format(plength[is_setosa].max()))
print('Minimum of others: {0}.'.format(plength[~is_setosa].min()))

这是书上的例子 却报错：

RESTART: C:\Users\Administrator\Desktop\1400OS_Code\1400OS_02_Codes\code\1.2\simple_threshold.py 
Traceback (most recent call last):
  File "C:\Users\Administrator\Desktop\1400OS_Code\1400OS_02_Codes\code\1.2\simple_threshold.py", line 2, in <module>
    from sklearn.datasets import load_iris
  File "D:\pythonIDE\lib\site-packages\sklearn\__init__.py", line 134, in <module>
    from .base import clone
  File "D:\pythonIDE\lib\site-packages\sklearn\base.py", line 11, in <module>
    from scipy import sparse
  File "D:\pythonIDE\lib\site-packages\scipy\sparse\__init__.py", line 229, in <module>
    from .csr import *
  File "D:\pythonIDE\lib\site-packages\scipy\sparse\csr.py", line 15, in <module>
    from ._sparsetools import csr_tocsc, csr_tobsr, csr_count_blocks, \
ImportError: DLL load failed: 找不到指定的模块。

很奇怪  。后来  我加了一句话 import matplotlib.pyplot as plt 而且只能加在最前面  像这样

import matplotlib.pyplot as plt
from sklearn.datasets import load_iris
import numpy as np

就不报错了  。

不知道这是什么问题 。希望高人指点。