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List:       wekalist
Subject:    [Wekalist] Regression with wrapper3
From:       bujarra <thecoderxxxxxxxxx () gmail ! com>
Date:       2021-04-14 22:12:38
Message-ID: 1618438358480-0.post () n7 ! nabble ! com
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Hi all,

I'm trying to use Alternating Model Tree as regression with wrapper3 using
Spyder (Python). I've followed the example in here
https://fracpete.github.io/python-weka-wrapper/examples.html

This is my code:

from weka.classifiers import PredictionOutput, KernelClassifier, Kernel
from weka.core.converters import Loader
from weka.classifiers import Evaluation
from weka.core.classes import Random

loader = Loader(classname="weka.core.converters.ArffLoader")
data = loader.load_file( "car_vila.arff")
data.class_is_last()

cls = KernelClassifier(classname="weka.classifiers.functions.SMOreg",
options=["-N", "0"])
kernel =
Kernel(classname="weka.classifiers.functions.supportVector.RBFKernel",
options=["-G", "0.1"])
cls.kernel = kernel
pout =
PredictionOutput(classname="weka.classifiers.evaluation.output.prediction.PlainText")
evl = Evaluation(data)
evl.crossvalidate_model(cls, data, 10, Random(1), pout)

print(evl.summary())
print(pout.buffer_content())

import weka.plot.classifiers as plcls  # NB: matplotlib is required
plcls.plot_classifier_errors(evl.predictions, wait=True)

I'm using the attached .arff file (I also tried with bolts.arff). However, I
get this error.


  File "C:\X.py", line 13, in <module>
    loader = Loader(classname="weka.core.converters.ArffLoader")

  File "C:\anaconda3\lib\site-packages\weka\core\converters.py", line 42, in
__init__
    jobject = Loader.new_instance(classname)

  File "C:\anaconda3\lib\site-packages\weka\core\classes.py", line 669, in
new_instance
    javabridge.class_for_name("java.lang.Object"), classname, [])

  File "C:\anaconda3\lib\site-packages\javabridge\jutil.py", line 1743, in
class_for_name
    ldr = static_call('java/lang/ClassLoader', 'getSystemClassLoader',

  File "C:\anaconda3\lib\site-packages\javabridge\jutil.py", line 939, in
static_call
    fn = make_static_call(class_name, method_name, sig)

  File "C:\anaconda3\lib\site-packages\javabridge\jutil.py", line 910, in
make_static_call
    klass = env.find_class(class_name)

AttributeError: 'NoneType' object has no attribute 'find_class' 

Which is the cause of the error? It looks the ArffLoader.

car_vila.arff <https://weka.8497.n7.nabble.com/file/t7341/car_vila.arff>  

Thanks in advance.



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