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How to properly use SMOTE for data balancing

I wanted to know if it is required to use SMOTE only after splitting test and train dataset. I used smote after train_test_split for Churn prediction, but haven't got any significant improvement pre or post SMOTE. Below is my entire code using smote. Not sure where the issue is. I wanted to know if I used SMOTE properly.
Below is the code
import pandas as pd
import numpy as np
from datetime import timedelta,datetime,date
import seaborn as sns
import matplotlib.pyplot as plt
%matplotlib inline
import warnings
warnings.filterwarnings('ignore')
from sklearn import linear_model
from sklearn.linear_model import LinearRegression
from numpy import percentile
tel_data = pd.read_csv('WA_Fn-UseC_-Telco-Customer-Churn.csv')
tel_data.info()
tel_data.isnull().sum()
num = {"No":0,"Yes":1}
tel_data = tel_data.replace({"Churn":num})
# also total charges seem to be object. coverting to integer
tel_data['TotalCharges'] = pd.to_numeric(tel_data['TotalCharges'])
tel_data.head(2)
tel_data['Churn'].value_counts()
plt.figure(figsize=(6,5))
sns.countplot(tel_data['Churn'])
plt.show()
# using pd.to_numeric to convert the TotalCharges column to numeric will help us see the null values
tel_data.TotalCharges = pd.to_numeric(tel_data.TotalCharges, errors="coerce")
tel_data.isnull().sum()
# deleting the rows with null values
tel_data = tel_data.dropna(axis=0)
# encoding all categorical variables using one hot encoding
tel_data = pd.get_dummies(tel_data,drop_first=True,columns=['gender','Partner','Dependents',
'PhoneService','MultipleLines','InternetService',
'OnlineSecurity','OnlineBackup','DeviceProtection',
'TechSupport','StreamingTV','StreamingMovies',
'Contract','PaperlessBilling','PaymentMethod'])
# splitting the dataset (removing 'customerID' since it doesnt serve any purpose)
X = tel_data.drop(['customerID','Churn'],axis=1)
y = tel_data['Churn']
# performing feature selection using chi2 test
from sklearn.feature_selection import chi2
chi_scores = chi2(X,y)
print('chi_values:',chi_scores[0],'\n')
print('p_values:',chi_scores[1])
p_values = pd.Series(chi_scores[1],index = X.columns)
p_values.sort_values(ascending = False , inplace = True)
plt.figure(figsize=(12,8))
p_values.plot.bar()
plt.show()
tel_data.drop(['PhoneService_Yes','gender_Male','MultipleLines_No phone service','MultipleLines_Yes','customerID'],axis=1,inplace=True)
tel_data.head(2)
# splitting the dataset (removing 'customerID' since it doesnt serve any purpose)
X = tel_data.drop(['Churn'],axis=1)
y = tel_data['Churn']
# import sklearn libraries
from sklearn.model_selection import train_test_split
from sklearn.metrics import classification_report,confusion_matrix
from sklearn.model_selection import RandomizedSearchCV
import xgboost as xgb
from sklearn.metrics import accuracy_score
# splitting into train and test data
from sklearn.model_selection import train_test_split
X_train,X_test,y_train,y_test = train_test_split(X,y,test_size=0.3,random_state=42,stratify=y)
model_xgb_1 = xgb.XGBClassifier(n_estimators=100,
learning_rate=0.3,
max_depth=5,
random_state=42 )
xgbmod = model_xgb_1.fit(X_train,y_train)
# checking accuracy of training data
print('Accuracy of XGB classifier on training set: {:.2f}'
.format(xgbmod.score(X_train, y_train)))
y_xgb_pred = trn_xgbmod.predict(X_test)
print(classification_report(y_test, y_xgb_pred))
from imblearn.over_sampling import SMOTE
smote_preprocess = SMOTE(random_state=42)
X_train_resampled,y_train_resampled = smote_preprocess.fit_resample(X_train,y_train)
model_xgb_smote = xgb.XGBClassifier(n_estimators=100,
learning_rate=0.3,
max_depth=5,
random_state=42 )
xgbmod_smote = model_xgb_smote.fit(X_train_resampled,y_train_resampled)
# checking accuracy of training data
print('Accuracy of XGB classifier on training set: {:.2f}'
.format(xgbmod_smote.score(X_train_resampled,y_train_resampled)))
y_xgb_pred_smote = xgbmod_smote.predict(X_test)
print(classification_report(y_test, y_xgb_pred_smote))

ROC curve for multi-class classification without one vs all in python

I have a multi-class classification problem with 9 different classes. I am using the AdaBoostClassifier class from scikit-learn to train my model without using the one vs all technique, as the number of classes is very high and it might be inefficient.
I have tried using the tips from the documentation in scikit learn [1], but there the one vs all technique is used, which is substantially different. In my approach I only get one prediction per event, i.e. if I have n classes, the outcome of the prediction is a single value within the n classes. For the one vs all approach, on the other hand, the outcome of the prediction is an array of size n with a sort of likelihood value per class.
[1]
https://scikit-learn.org/stable/auto_examples/model_selection/plot_roc.html#sphx-glr-auto-examples-model-selection-plot-roc-py
The code is:
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt # Matplotlib plotting library for basic visualisation
%matplotlib inline
from sklearn.model_selection import train_test_split
from sklearn.ensemble import AdaBoostClassifier
from sklearn.metrics import accuracy_score
from sklearn.tree import DecisionTreeClassifier
from sklearn.metrics import roc_curve, auc
from sklearn import preprocessing
# Read data
df = pd.read_pickle('data.pkl')
# Create the dependent variable class
# This will substitute each of the n classes from
# text to number
factor = pd.factorize(df['target_var'])
df.target_var= factor[0]
definitions = factor[1]
X = df.drop('target_var', axis=1)
y = df['target_var]
X_train, X_test, y_train, y_test = train_test_split(X, y, random_state = 0)
bdt_clf = AdaBoostClassifier(
DecisionTreeClassifier(max_depth=2),
n_estimators=250,
learning_rate=0.3)
bdt_clf.fit(X_train, y_train)
y_pred = bdt_clf.predict(X_test)
#Reverse factorize (converting y_pred from 0s,1s, 2s, etc. to their original values
reversefactor = dict(zip(range(9),definitions))
y_test_rev = np.vectorize(reversefactor.get)(y_test)
y_pred_rev = np.vectorize(reversefactor.get)(y_pred)
I tried directly with the roc curve function, and also binarising the labels, but I always get the same error message.
def multiclass_roc_auc(y_test, y_pred):
lb = preprocessing.LabelBinarizer()
lb.fit(y_test)
y_test = lb.transform(y_test)
y_pred = lb.transform(y_pred)
return roc_curve(y_test, y_pred)
multiclass_roc_auc(y_test, y_pred_test)
The error message is:
ValueError: multilabel-indicator format is not supported
How could this be sorted out? Am I missing some important concept?

ValueError: Can't handle mix of continuous and multiclass

I want to estimate the model from the data I've used here in scikit-learn. I am using the DecisionTreeClassifier.score function but when running the code I'll receive an ValueError:
Can't handle mix of continuous and multiclass.
Here is the code I use:
from sklearn import datasets
import pandas as pd
import matplotlib.pyplot as plt
import numpy as np
from sklearn.model_selection import train_test_split
from sklearn.tree import DecisionTreeClassifier
nba = pd.read_excel(r"C:\Users\user\Desktop\nba.xlsx")
X = nba.drop('平均得分', axis = 1)
y = nba['平均得分']
X_train, X_test, y_train, y_test = train_test_split(
X, y, test_size = 0.20)
nba_tree = DecisionTreeClassifier()
nba_tree.fit(X_train, y_train.astype('int'))
y_pred = nba_tree.predict(X_test)
nba_tree.score(X_test, y_test)

It looks like your target variable 平均得分 is a continuous variable. Probably you are try to solve a regression problem. If that is the case then try DecisionTreeRegressor instead of DecisionTreeClassifier.

Plot feature importance with xgboost

When I plot the feature importance, I get this messy plot. I have more than 7000 variables. I understand the built-in function only selects the most important, although the final graph is unreadable.
This is the complete code:
import numpy as np
import pandas as pd
df = pd.read_csv('ricerice.csv')
array=df.values
X = array[:,0:7803]
Y = array[:,7804]
from xgboost import XGBClassifier
from sklearn.model_selection import train_test_split
from sklearn.metrics import accuracy_score
seed=0
test_size=0.30
X_train, X_test, y_train, y_test = train_test_split(X,Y,test_size=test_size, random_state=seed)
from xgboost import XGBClassifier
model = XGBClassifier()
model.fit(X, Y)
import matplotlib.pyplot as plt
from matplotlib import pyplot
from xgboost import plot_importance
fig1=plt.gcf()
plot_importance(model)
plt.draw()
fig1.savefig('xgboost.png', figsize=(50, 40), dpi=1000)
Although the size of the figure, the graph is illegible.

There are couple of points:
To fit the model, you want to use the training dataset (X_train, y_train), not the entire dataset (X, y).
You may use the max_num_features parameter of the plot_importance() function to display only top max_num_features features (e.g. top 10).
With the above modifications to your code, with some randomly generated data the code and output are as below:
import numpy as np
# generate some random data for demonstration purpose, use your original dataset here
X = np.random.rand(1000,100) # 1000 x 100 data
y = np.random.rand(1000).round() # 0, 1 labels
from xgboost import XGBClassifier
from sklearn.model_selection import train_test_split
from sklearn.metrics import accuracy_score
seed=0
test_size=0.30
X_train, X_test, y_train, y_test = train_test_split(X,y,test_size=test_size, random_state=seed)
from xgboost import XGBClassifier
model = XGBClassifier()
model.fit(X_train, y_train)
import matplotlib.pylab as plt
from matplotlib import pyplot
from xgboost import plot_importance
plot_importance(model, max_num_features=10) # top 10 most important features
plt.show()

You need to sort your feature importances in descending order first:
sorted_idx = trained_mdl.feature_importances_.argsort()[::-1]
Then just plot them with the column names from your dataframe
from matplotlib import pyplot as plt
n_top_features = 10
sorted_idx = trained_mdl.feature_importances_.argsort()[::-1]
plt.barh(X_test.columns[sorted_idx][:n_top_features ], trained_mdl.feature_importances_[sorted_idx][:n_top_features ])

You can obtain feature importance from Xgboost model with feature_importances_ attribute. In your case, it will be:
model.feature_imortances_
This attribute is the array with gain importance for each feature. Then you can plot it:
from matplotlib import pyplot as plt
plt.barh(feature_names, model.feature_importances_)
(feature_names is a list with features names)
You can sort the array and select the number of features you want (for example, 10):
sorted_idx = model.feature_importances_.argsort()
plt.barh(feature_names[sorted_idx][:10], model.feature_importances_[sorted_idx][:10])
plt.xlabel("Xgboost Feature Importance")
There are two more methods to get feature importance:
you can use permutation_importance from scikit-learn (from version 0.22)
you can use SHAP values
You can read more in this blog post of mine.

What is the Python code to show the feature importance in SVM?

How can I show the important features that contribute to the SVM model along with the feature name?
My code is shown below,
First I Imported the modules
from sklearn.preprocessing import StandardScaler
from sklearn.pipeline import Pipeline
from sklearn.grid_search import GridSearchCV
from sklearn.metrics import accuracy_score
from sklearn.preprocessing import StandardScaler
from sklearn.pipeline import Pipeline
from sklearn.svm import SVC
from sklearn.model_selection import cross_val_score
from sklearn.model_selection import GridSearchCV
from sklearn.model_selection import train_test_split
from sklearn.metrics import confusion_matrix, classification_report
Then I divided my data into features and variables
y = df_new[['numeric values']]
X = df_new.drop('numeric values', axis=1).values
Then I Setup the pipeline
steps = [('scalar', StandardScaler()),
('SVM', SVC(kernel='linear'))]
pipeline = Pipeline(steps)
Then I Specified my the hyperparameter space
parameters = {'SVM__C':[1, 10, 100],
'SVM__gamma':[0.1, 0.01]}
I Created a train and test sets
X_train, X_test, y_train, y_test = train_test_split(X,y, test_size = 0.2, random_state=21)
Instantiate the GridSearchCV object: cv
cv = GridSearchCV(pipeline,param_grid = parameters,cv=5)
Fit to the training set
cv.fit(X_train,y_train.values.ravel())
Predict the labels of the test set: y_pred
y_pred = cv.predict(X_test)
feature_importances = cv.best_estimator_.feature_importances_
The error message I get
'Pipeline' object has no attribute 'feature_importances_'

What I understood is that, lets suppose you are building a model with 100 feature and you want to know which feature is more important and which is less if this is the case ?
Just try Uni-variate feature selection method, Its very basic method and you can play with this before going to advance methods for your data. Sample code is provided scikit-learn it self. You can modified it as per your requirement.
print(__doc__)
import numpy as np
import matplotlib.pyplot as plt
from sklearn import datasets, svm
from sklearn.feature_selection import SelectPercentile, f_classif
###############################################################################
# import some data to play with
# The iris dataset
iris = datasets.load_iris()
# Some noisy data not correlated
E = np.random.uniform(0, 0.1, size=(len(iris.data), 20))
# Add the noisy data to the informative features
X = np.hstack((iris.data, E))
y = iris.target
###############################################################################
plt.figure(1)
plt.clf()
X_indices = np.arange(X.shape[-1])
###############################################################################
# Univariate feature selection with F-test for feature scoring
# We use the default selection function: the 10% most significant features
selector = SelectPercentile(f_classif, percentile=10)
selector.fit(X, y)
scores = -np.log10(selector.pvalues_)
scores /= scores.max()
plt.bar(X_indices - .45, scores, width=.2,
label=r'Univariate score ($-Log(p_{value})$)', color='g')
###############################################################################
# Compare to the weights of an SVM
clf = svm.SVC(kernel='linear')
clf.fit(X, y)
svm_weights = (clf.coef_ ** 2).sum(axis=0)
svm_weights /= svm_weights.max()
plt.bar(X_indices - .25, svm_weights, width=.2, label='SVM weight', color='r')
clf_selected = svm.SVC(kernel='linear')
clf_selected.fit(selector.transform(X), y)
svm_weights_selected = (clf_selected.coef_ ** 2).sum(axis=0)
svm_weights_selected /= svm_weights_selected.max()
plt.bar(X_indices[selector.get_support()] - .05, svm_weights_selected,
width=.2, label='SVM weights after selection', color='b')
plt.title("Comparing feature selection")
plt.xlabel('Feature number')
plt.yticks(())
plt.axis('tight')
plt.legend(loc='upper right')
plt.show()
Code ref.
http://scikit-learn.org/0.15/auto_examples/plot_feature_selection.html
Note;
For each feature, this method will plot p-values for the univariate feature selection and the corresponding weights of an SVM. This method selects those feature which shows larger SVM weights.