Shannon’s entropy

Metric calculating the Shannon’s entropy of the batch/group variable within each cell’s k-nearest neigbours. Shannon’s entropy can be written as: \[entropy = -\sum_{i=1}^{n}p(x_i)*\log(p(x_i))\]. Thereby \(p(x_i)\) describes the probability of batch i in the neighborhood of a specific cell. This probability is the proportion of the observed number of cells from each batch within the knn. We divide each cell’s Shannon’s entropy by \(\log(\#batches)\) to ensure a value in \([0:1]\).