近红外光谱建模之样本集划分python实现（SPXY算法）

一 SPXY算法原理

SPXY算法原理（sample set partitioning based on joint x-y distance）：它是在KS算法基础上发展而来的，SPXY在样品间距离计算时将x变量和y变量同时考虑在内，其距离公式如下：

二 python代码实现

def spxy(x, y, test_size=0.2):
    """

    :param x: shape (n_samples, n_features)
    :param y: shape (n_sample, )
    :param test_size: the ratio of test_size
    :return: spec_train :(n_samples, n_features)
             spec_test: (n_samples, n_features)
             target_train: (n_sample, )
             target_test: (n_sample, )
    """
    x_backup = x
    y_backup = y   
    M = x.shape[0]            
    N = round((1-t