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How to correct the NameError: name 'xx' is not defined? - Printable Version

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How to correct the NameError: name 'xx' is not defined? - vokoyo - Apr-03-2019

May I know how to correct the NameError: name 'xx' is not defined ?
import numpy as np
import matplotlib.pyplot as plt
from sklearn import svm, datasets
# import some data to play with
iris = datasets.load_iris()
X = iris.data[:,[2,3]]
y = iris.target

def plotSVC(title):
# create a mesh to plot in
    x_min, x_max = X[:, 0].min() - 1, X[:, 0].max() + 1
    y_min, y_max = X[:, 1].min() - 1, X[:, 1].max() + 1
    h = (x_max / x_min)/100
    xx, yy = np.meshgrid(np.arange(x_min, x_max, h),
             np.arange(y_min, y_max, h))
    plt.subplot(1, 1, 1)
    Z = svc.predict(np.c_[xx.ravel(), yy.ravel()])
    Z = Z.reshape(xx.shape)

cs = [0.1, 1, 10, 100]
for c in cs:
    svc = svm.SVC(kernel='rbf', C=c).fit(X, y)
    plotSVC('C=' + str(c))
plt.contourf(xx, yy, Z, cmap=plt.cm.Paired, alpha=0.8)
plt.scatter(X[:, 0], X[:, 1], c=y, cmap=plt.cm.Paired)
plt.xlabel('petal length')
plt.ylabel('petal width')
plt.xlim(xx.min(), xx.max())
plt.show()
Please see the attached files -
click to show images
Please help me so that I can improve my computing skills

RE: How to correct the NameError: name 'xx' is not defined? - Larz60+ - Apr-03-2019

Please post complete unaltered error traceback message in BBCode error tags.
Thank You

RE: How to correct the NameError: name 'xx' is not defined? - ichabod801 - Apr-03-2019

Do us a favor and don't post a ton of images like that.

Your problem is that xx (and yy and Z) are defined in the function plotSVC. You can't access them outside the function unless you use a return statement and an assignment to get them out of the function:

def one23():
   return 1, 2, 3
one, two, three = one23()
print(two)


RE: How to correct the NameError: name 'xx' is not defined? - vokoyo - Apr-03-2019

The error message - 



Error:
runfile('C:/Users/HSIPL/Desktop/New f/a i/Homework 5 6 Solution draft.py', wdir='C:/Users/HSIPL/Desktop/New f/a i')
C:/Users/HSIPL/Desktop/New f/a i/Homework 5 6 Solution draft.py:13: RuntimeWarning: divide by zero encountered in double_scalars
  h = (x_max / x_min)/100
C:\Users\HSIPL\Anaconda3\lib\site-packages\matplotlib\cbook\deprecation.py:107: MatplotlibDeprecationWarning: Adding an axes using the same arguments as a previous axes currently reuses the earlier instance.  In a future version, a new instance will always be created and returned.  Meanwhile, this warning can be suppressed, and the future behavior ensured, by passing a unique label to each axes instance.
  warnings.warn(message, mplDeprecation, stacklevel=1)
Traceback (most recent call last):

  File "<ipython-input-2-9e53960ad79d>", line 1, in <module>
    runfile('C:/Users/HSIPL/Desktop/New f/a i/Homework 5 6 Solution draft.py', wdir='C:/Users/HSIPL/Desktop/New f/a i')

  File "C:\Users\HSIPL\Anaconda3\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 668, in runfile
    execfile(filename, namespace)

  File "C:\Users\HSIPL\Anaconda3\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 108, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "C:/Users/HSIPL/Desktop/New f/a i/Homework 5 6 Solution draft.py", line 24, in <module>
    plt.contourf(xx, yy, Z, cmap=plt.cm.Paired, alpha=0.8)

NameError: name 'xx' is not defined
How to write the new coding for correct programming ?

RE: How to correct the NameError: name 'xx' is not defined? - nilamo - Apr-03-2019

The variable isn't defined. You can't use a variable that isn't defined. So to solve the error, you can either:

1) Define the variable, and set it with whatever value makes sense in the context, or
2) Not try to use it anymore.

RE: How to correct the NameError: name 'xx' is not defined? - delonbest - Feb-17-2021

In most cases, this error is triggered when Python sees a variable name (Global or Local) and doesn't know what it's for. These errors can happen if you forget to initialize a variable , if you misspell a variable, or if you misspell a reserved word such as "True". Before you use the global variable in your function for reading, it must be first initialized somewhere: either outside of the function or inside it.