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# 204.6.6 Practice : Kernel – Non Linear Classifier

##### Putting Kernels into practice.

Link to the previous post : https://statinfer.com/204-6-5-the-non-linear-decision-boundary/

In this session we will practice non linear kernels of SVM in python.

### Practice : Kernel – Non linear classifier

• Dataset : Software users/sw_user_profile.csv
• How many variables are there in software user profile data?
• Plot the active users against and check weather the relation between age and “Active” status is linear or non-linear.
• Build an SVM model(model-1), make sure that there is no kernel or the kernel is linear.
• For model-1, create the confusion matrix and find out the accuracy.
• Create a new variable. By using the polynomial kernel.
• Build an SVM model(model-2), with the new data mapped on to higher dimensions. Keep the default kernel as linear.
• For model-2, create the confusion matrix and find out the accuracy.
• Plot the SVM with results.
• With the original data re-cerate the model(model-3) and let python choose the default kernel function.
• What is the accuracy of model-3?
In [19]:
```#Dataset : Software users/sw_user_profile.csv
```
In [20]:
```#How many variables are there in software user profile data?
sw_user_profile.shape
```
Out[20]:
`(490, 3)`
In [21]:
```#Plot the active users against and check weather the relation between age and "Active" status is linear or non-linear
plt.scatter(sw_user_profile.Age,sw_user_profile.Id,color='blue')
```
Out[21]:
`<matplotlib.collections.PathCollection at 0xce7ac50>`
In [22]:
```#Build an SVM model(model-1), make sure that there is no kernel or the kernel is linear

#Model Building
X= sw_user_profile[['Age']]
y= sw_user_profile[['Active']].values.ravel()
Linsvc = svm.SVC(kernel='linear', C=1).fit(X, y)
```
In [23]:
```#Predicting values
predict3 = Linsvc.predict(X)
```
In [27]:
```#For model-1, create the confusion matrix and find out the accuracy
#Confusion Matrix
from sklearn.metrics import confusion_matrix
conf_mat = confusion_matrix(sw_user_profile[['Active']],predict3)
conf_mat
```
Out[27]:
```array([[317,   0],
[173,   0]])```
In [28]:
```#Accuracy
Accuracy3 = Linsvc.score(X, y)
Accuracy3
```
Out[28]:
`0.64693877551020407`

New variable derivation. Mapping to higher dimensions

In [29]:
```#Standardizing the data to visualize the results clearly
sw_user_profile['age_nor']=(sw_user_profile.Age-numpy.mean(sw_user_profile.Age))/numpy.std(sw_user_profile.Age)
```
In [30]:
```#Create a new variable. By using the polynomial kernel
#Creating the new variable
sw_user_profile['new']=(sw_user_profile.age_nor)*(sw_user_profile.age_nor)
```
In [31]:
```#Build an SVM model(model-2), with the new data mapped on to higher dimensions. Keep the default kernel as linear

#Model Building with new variable
X= sw_user_profile[['Age']+['new']]
y= sw_user_profile[['Active']].values.ravel()
Linsvc = svm.SVC(kernel='linear', C=1).fit(X, y)
predict4 = Linsvc.predict(X)
```
In [32]:
```#For model-2, create the confusion matrix and find out the accuracy
#Confusion Matrix
conf_mat = confusion_matrix(sw_user_profile[['Active']],predict4)
conf_mat
```
Out[32]:
```array([[317,   0],
[  0, 173]])```
In [33]:
```#Accuracy
Accuracy4 = Linsvc.score(X, y)
Accuracy4
```
Out[33]:
`1.0`
In [34]:
```#With the original data re-cerate the model(model-3) and let python choose the default kernel function.
########Model Building with radial kernel function
X= sw_user_profile[['Age']]
y= sw_user_profile[['Active']].values.ravel()
Linsvc = svm.SVC(kernel='rbf', C=1).fit(X, y)
predict5 = Linsvc.predict(X)
conf_mat = confusion_matrix(sw_user_profile[['Active']],predict5)
conf_mat
```
Out[34]:
```array([[317,   0],
[  0, 173]])```
In [35]:
```#Accuracy model-3
Accuracy5 = Linsvc.score(X, y)
Accuracy5
```
Out[35]:
```1.0

The next post is about soft margin classification noisy data.
Link to the next post : https://statinfer.com/204-6-7-soft-margin-classification-noisy-data/```
21st June 2017