This function reads the CNV ratio data
broad.mit.edu_PANCAN_Genome_Wide_SNP_6_whitelisted.gene.xena, in which
CNV ratios were calculated by dividing, for each gene, the estimated
gene-level CNV values in malignant tumors to the average CNV value in
normal adjacent tissues (NATs) of the same cancer type.
.get_TCGA_CNV_ratio()a data frame that contains CNV ratio data for each tumor
The function also removes possible duplicated tumor samples and samples with NAs in the dataset.
It should not be used directly, only inside initialize_cnv_data()
function.
Other helper function for data initialization:
.get_TCGA_CNV_value(),
.get_TCGA_CNV(),
.get_TCGA_GTEX_RNAseq(),
.get_TCGA_RNAseq()
if (FALSE) {
.get_TCGA_CNV_ratio()
}