Function returns ndarray of gene expression values from ndarray of unmodified data set and ndarray of gene indices
    :param unparsedArr: numpy ndarray of unmodified data set
    :param nnGeneIndex: numpy ndarray of indices of genes of interest
    :return nnGeneExp:  numpy ndarray of data set including all cells and expression data only of genes of interest

def mkIndexedArr(unparsedArr,nnGeneIndex):
    '''
    Function returns ndarray of gene expression values from ndarray of unmodified data set and ndarray of gene indices
    :param unparsedArr: numpy ndarray of unmodified data set
    :param nnGeneIndex: numpy ndarray of indices of genes of interest
    :return nnGeneExp:  numpy ndarray of data set including all cells and expression data only of genes of interest 
    '''
    nnGeneExp=np.zeros([unparsedArr.shape[0],nnGeneIndex.shape[0]],dtype=float) #initializes new array for output
    for i in range(0,nnGeneIndex.shape[0]): #fill in the new array based on indices of interest
        nnGeneExp[:,i]=unparsedArr[:,nnGeneIndex[i]]
    return nnGeneExp