import cv2
 import numpy as np


 samples = np.loadtxt('generalsamples.data',np.float32)
 responses = np.loadtxt('generalresponses.data',np.float32)
 responses = responses.reshape((responses.size,1))

 print "samples: n",samples
 print "respnses: n",responses

 model = cv2.ml.KNearest_create()
 model.train(samples,cv2.ml.ROW_SAMPLE,responses)

samples:

[ 1.   1.   1.   1.   1.   1.   1.   1.   1.  65.   0.   0.   0.   0.   0.
  0.   0.   1.  65.   0.   0.   0.   0.   0.   0.   0.   1.  49.  16.   0.
  0.   0.   0.   0.   0.   1.   1.  65.   0.   0.   0.   0.   0.   0.   1.
  1.  65.   0.   0.   0.   0.   0.   0.   0.   1.  65.   0.   0.   0.   0.
  0.   0.   0.   1.  65.   0.   0.   0.   0.   0.   0.   0.   1.  65.   0.
  0.   0.   0.   0.   0.   0.   1.  11.  55.   0.   0.   0.   0.   0.   0.
  1.   4.  62.   0.   0.   0.   0.   0.   0.   0.]

respnses:
[[ 7.]]

Traceback (most recent call last):
  File "test.py", line 10, in <module>
    model.train(samples,cv2.ml.ROW_SAMPLE,responses)
cv2.error: OpenCV(4.0.0-pre) /home/shajal/opencv/opencv/modules/ml/src/data.cpp:259: error: (-215:Assertion failed) samples.type() == 5 || samples.type() == 4 in function 'setData'