Question

我在Mc Os X 10.9.4上安装了weka python包装器。我尝试运行示例代码：

import weka.core.jvm as jvm
jvm.start()

from weka.core.converters import Loader
l = Loader("weka.core.converters.ArffLoader")
d = l.load_file("X.arff")

d.set_class_index(d.num_attributes() - 1)
print(d)

我收到以下错误：

Failed to get class weka/core/converters/ArffLoader
Exception in thread "Thread-2" java.lang.NoClassDefFoundError: weka/core/converters/ArffLoader
Failed to instantiate weka.core.converters.ArffLoader/weka/core/converters/ArffLoader: weka/core/converters/ArffLoader
Caused by: java.lang.ClassNotFoundException: weka.core.converters.ArffLoader
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Traceback (most recent call last):
  File "/Users/hani/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/IPython/core/interactiveshell.py", line 2883, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-5-d835d9d560d2>", line 2, in <module>
    l = Loader("weka.core.converters.ArffLoader")
  File "/Users/hani/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/python_weka_wrapper-0.1.10-py2.7.egg/weka/core/converters.py", line 40, in __init__
    self.enforce_type(jobject, "weka.core.converters.Loader")
  File "/Users/hani/Library/Enthought/Canopy_64bit/User/lib/python2.7/site-packages/python_weka_wrapper-0.1.10-py2.7.egg/weka/core/classes.py", line 113, in enforce_type
    raise TypeError("Object does not implement or subclass " + intf_or_class + "!")
TypeError: Object does not implement or subclass weka.core.converters.Loader!

经过一些修改后，我意识到使用os.chdir将工作目录设置为python-weka-wrapper文件夹可以解决某些环境中的问题，但不能解决所有这些问题（例如pycharm没有使用此技巧修复）。我有什么想法可以解决这个问题吗？

Answer 1

显然，使用weka jar文件的路径调用jvm可以解决问题：

jvm.start(class_path=['/some/where/python-weka-wrapper.jar', 
'/some/where/weka.jar'])

感谢Peter Reutemann的回复。

Weka python包装器

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