Python3|Python3 TypeError: only size-1 arrays can be converted to Python scalars Python3TypeError:onlysize-1arrayscan

问题：在用python3使用knn.train(trainData, responses)的时候，可能会产生错误：TypeError: only size-1 arrays can be converted to Python scalars

newcomer = np.random.randint(0, 100, (1, 2)).astype(np.float32) plt.scatter(newcomer[:, 0], newcomer[:, 1], 80, 'g', 'o') knn = cv2.ml.KNearest_create() knn.train(trainData, responses)

报错信息：

--------------------------------------------------------------------------- TypeErrorTraceback (most recent call last) in () 2 plt.scatter(newcomer[:, 0], newcomer[:, 1], 80, 'g', 'o') 3 knn = cv2.ml.KNearest_create() ----> 4 knn.train(trainData, responses) 5 TypeError: only size-1 arrays can be converted to Python scalars

解决：将knn.train(trainData, responses)替换为：
knn.train(trainData, cv2.ml.ROW_SAMPLE, responses)
分析：
在python3中，knn.train需要传入layout参数，如第二种构造方法

Docstring: train(trainData[, flags]) -> retval .@brief Trains the statistical model . .@param trainData training data that can be loaded from file using TrainData::loadFromCSV or .created with TrainData::create. .@param flags optional flags, depending on the model. Some of the models can be updated with the .new training samples, not completely overwritten (such as NormalBayesClassifier or ANN_MLP).train(samples, layout, responses) -> retval .@brief Trains the statistical model . .@param samples training samples .@param layout See ml::SampleTypes. .@param responses vector of responses associated with the training samples. Type:builtin_function_or_method

变更样例：

knn.train(trainData, cv2.ml.ROW_SAMPLE, responses)

参考文章：http://www.itkeyword.com/doc/6947006191723413x615/knn-train-in-cv2-with-opencv-3-0
说明：问题产生的环境
Python版本：3.6.5
OpenCV版本：3.4.2
【Python3|Python3 TypeError: only size-1 arrays can be converted to Python scalars】转自：https://blog.csdn.net/yuxuan_08/article/details/87966958