如何使用 python 中的人工神经网络预测 label 的新输入值

Question

I am new in machine learning. I am making a Streamlit app for multiclass classification using artificial neural network. My question is about the ANN model, not about the Streamlit. I know I can use MLPClassifier, but I want to build and train my own model. So, I used the following code to analyze the following data. -

import numpy as np
import matplotlib.pyplot as plt
import tensorflow as tf
import seaborn as sns
import warnings
warnings.filterwarnings('ignore')
import tensorflow as tf
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense, Activation
from tensorflow.keras.callbacks import EarlyStopping
from tensorflow.keras.optimizers import Adam
from tensorflow.keras.layers import Dropout

from sklearn.metrics import classification_report, confusion_matrix
from sklearn.metrics import plot_roc_curve, roc_auc_score, roc_curve
from sklearn.model_selection import cross_val_score, cross_validate
from sklearn.model_selection import GridSearchCV

df=pd.read_csv("./Churn_Modelling.csv")
#Drop Unwanted features
df.drop(columns=['Surname','RowNumber','CustomerId'],inplace=True)
df.head()

#Label Encoding of Categ features
df['Geography']=df['Geography'].map({'France':0,'Spain':1,'Germany':2})
df['Gender']=df['Gender'].map({'Male':0,'Female':1})

#Input & Output selection
X=df.drop('Exited',axis=1)
Y = df['Exited']
Y = df['Exited'].map({'yes':1, 'no':2, 'maybe':3})

#train test split
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=12,stratify=Y)

#scaling 
from sklearn.preprocessing import StandardScaler
ss = StandardScaler()
X_train = ss.fit_transform(X_train)
Y_train = ss.fit_transform(Y_train)
X_test=ss.transform(X_test)

# build a model
#build ANN
model=Sequential()
model.add(Dense(units=30,activation='relu',input_shape=(X.shape[1],)))
model.add(Dropout(rate = 0.2))
model.add(Dense(units=18,activation='relu'))
model.add(Dropout(rate = 0.1))
model.add(Dense(units=1,activation='sigmoid'))
model.compile(optimizer = 'adam', loss = 'binary_crossentropy', metrics = ['accuracy'])
       
#create callback : -
cb=EarlyStopping(
    monitor="val_loss",  #val_loss means testing error
    min_delta=0.00001, #value of lambda 
    patience=15,
    verbose=1,
    mode="auto", #minimize loss  #maximize accuracy
    baseline=None,
    restore_best_weights=False
)

trained_model=model.fit(X_train,Y_train,epochs=10,
                        validation_data=(X_test,Y_test),
                        callbacks=cb,
                        batch_size=10
                        )

model.evaluate(X_train,Y_train)
print("Training accuracy :",model.evaluate(X_train,Y_train)[1])
print("Training loss :",model.evaluate(X_train,Y_train)[0])

model.evaluate(X_test,Y_test)
print("Testing accuracy :",model.evaluate(X_test,Y_test)[1])
print("Testing loss :",model.evaluate(X_test,Y_test)[0])


y_pred_prob=model.predict(X_test)
y_pred=np.argmax(y_pred_cv, axis=-1)

print(classification_report(Y_test,y_pred))
print(confusion_matrix(Y_test,y_pred))

plt.figure(figsize=(7,5))
sns.heatmap(confusion_matrix(Y_test,y_pred),annot=True,cmap="OrRd_r",
            fmt="d",cbar=True,
            annot_kws={"fontsize":15})
plt.xlabel("Actual Result")
plt.ylabel("Predicted Result")
plt.show()

Then, I will save the model either by using pickle as follows-

# pickle_out = open("./my_model.pkl", mode = "wb") 
# pickle.dump(my_model, pickle_out) 
# pickle_out.close()

or as follows-

model.save('./my_model.h5')

Now, I want to predict the label (ie 'yes', 'no', 'maybe' etc.) of output variable 'Existed' based on new input values (as shown in the following table) that will be provided by an user - .

My question is that how should I save and load the model followed by predicting the labels for 'Existed' variable, so that it will automatically fill up the empty cell of Exited column with respective labels (ie 'yes', 'no', 'maybe' etc.).

I will appreciate your insightful comments on this post.

Answer 1

Once you have your model trained, you can simply run model.predict with the data you wish to predict on. Tricky parts of this process involve making sure this data is the right shape and that the indices match up.

I typically use this recipe:

Note that the features need to be in the exact same shape and order that the model was trained with.

to_predict = df[features]
predictions = model.predict(
    to_predict.to_numpy().reshape(-1, len(features))
)

predictions should be the same length as to_predict and it will be an np.array . You can get this back into a DataFrame with the same indices as to_predict by using

predictions = pd.DataFrame(
            predictions,
            columns="predicted_value",  # Anything you want
            index=to_predict.index,
        )

In your case, this should give values of 0, 1, 2. You will need to map these values back to 'yes', 'no', 'maybe'. To avoid overcomplicating things, you can just use a map on this new DataFrame :

predictions["predicted_value"] = predictions["predicted_value"].map({0: 'yes', 1: 'no', 2: 'maybe'})

Now we need to merge these predictions back with the original df :

df = df.merge(
    predictions, left_index=True, right_index=True, how="outer"
)