# multilabel classfication
from sklearn.multiclass import OneVsRestClassifier

# Linear Models
from sklearn.linear_model import LogisticRegression
from sklearn.discriminant_analysis import LinearDiscriminantAnalysis
from sklearn.svm import LinearSVC
from sklearn.naive_bayes import MultinomialNB
from lightgbm import LGBMClassifier

def train_classifier(X_train, y_train, X_valid=None, y_valid=None, C=1.0, model='lr'):
    """
      X_train, y_train — training data
      
      return: trained classifier
      
    """
    
    if model=='lr':
        model = LogisticRegression(C=C, penalty='l1', solver='liblinear')
        model = OneVsRestClassifier(model)
        model.fit(X_train, y_train)
    
    elif model=='svm':
        model = LinearSVC(C=C, penalty='l1', loss='squared_hinge')
        model = OneVsRestClassifier(model)
        model.fit(X_train, y_train)
    
    elif model=='nbayes':
        model = MultinomialNB(alpha=1.0)
        model = OneVsRestClassifier(model)
        model.fit(X_train, y_train)
        
    elif model=='lda':
        model = LinearDiscriminantAnalysis(solver='svd')
        model = OneVsRestClassifier(model)
        model.fit(X_train, y_train)

    return model