Análisis del Discriminante Cuadrático en Python.

library(reticulate)

Cargando las librerías necesarias.

#LOAD NECESSARY LIBRARIES
from sklearn.model_selection import train_test_split
from sklearn.discriminant_analysis import QuadraticDiscriminantAnalysis
from sklearn.model_selection import RepeatedStratifiedKFold
from sklearn.model_selection import cross_val_score
from sklearn import datasets
import matplotlib.pyplot as plt
import pandas as pd
import numpy as np

Cargando y viendo el iris dataset.

#LOAD AND VIEW IRIS DATASET
iris = datasets.load_iris()
df = pd.DataFrame(data = np.c_[iris['data'], iris['target']],
                 columns = iris['feature_names'] + ['target'])
df['species'] = pd.Categorical.from_codes(iris.target, iris.target_names)
df.columns = ['s_length', 's_width', 'p_length', 'p_width', 'target', 'species']
print(df.head())
##    s_length  s_width  p_length  p_width  target species
## 0       5.1      3.5       1.4      0.2     0.0  setosa
## 1       4.9      3.0       1.4      0.2     0.0  setosa
## 2       4.7      3.2       1.3      0.2     0.0  setosa
## 3       4.6      3.1       1.5      0.2     0.0  setosa
## 4       5.0      3.6       1.4      0.2     0.0  setosa
len(df.index)
## 150

Definiendo el predictor y las variables respuesta.

#DEFINE PREDICTOR AND RESPONSE VARIABLES
X = df[['s_length', 's_width', 'p_length', 'p_width']]
y = df['species']

Estimando el modelo Discriminante Cuadrático.

#FIT LDA MODEL
model = QuadraticDiscriminantAnalysis()
model.fit(X, y)
## QuadraticDiscriminantAnalysis()

Definiendo el modelo a evaluar.

#DEFINE METHOD TO EVALUATE MODEL
cv = RepeatedStratifiedKFold(n_splits=10, n_repeats=3, random_state=1)

Evaluando el modelo

#EVALUATE MODEL
#scores = cross_val_score(model, X, y, scoring='accuracy', cv=cv, n_jobs=-1)
#print(np.mean(scores))

Usando el modelo para predecir una nueva observación.

#USE MODEL TO MAKE PREDICTION ON NEW OBSERVATION
new = [5, 3, 1, .4]
model.predict([new])
## array(['setosa'], dtype=object)