Estoy tratando de ejecutar k-vecinos más cercanos usando cv2 (python 2.7) y opencv 3.0. He replicado el mismo mensaje de error usando código comohttp://docs.opencv.org/3.0-beta/doc/py_tutorials/py_ml/py_knn/py_knn_understanding/py_knn_understanding.html:

import cv2
import numpy as np
import matplotlib.pyplot as plt
# Feature set containing (x,y) values of 25 known/training data
trainData = np.random.randint(0,100,(25,2)).astype(np.float32)
# Labels each one either Red or Blue with numbers 0 and 1
responses = np.random.randint(0,2,(25,1)).astype(np.float32)
# Take Red families and plot them
red = trainData[responses.ravel()==0]
plt.scatter(red[:,0],red[:,1],80,'r','^')
# Take Blue families and plot them
blue = trainData[responses.ravel()==1]
plt.scatter(blue[:,0],blue[:,1],80,'b','s')
plt.show()
newcomer = np.random.randint(0,100,(1,2)).astype(np.float32)
plt.scatter(newcomer[:,0],newcomer[:,1],80,'g','o')

#The following line is modified for OpenCV 3.0
knn = cv2.ml.KNearest_create()
knn.train(trainData,responses)
ret, results, neighbours ,dist = knn.find_nearest(newcomer, 3)

print "result: ", results,"\n"
print "neighbours: ", neighbours,"\n"
print "distance: ", dist

plt.show()

Modifiqué la líneaknn = cv2.ml.KNearest_create () para OpenCV 3, pero la línea siguiente produce un error "TypeError: solo las matrices de longitud 1 se pueden convertir a escalares de Python" y no puedo entender qué debo usar para la función de tren.