This function reads the threshold CNV data
Gistic2_CopyNumber_Gistic2_all_thresholded.by_genes, which grouped the
CNV values with thresholds 3+, 3, 2, 1, 0, to represent high-level copy
number gain, low-level copy number gain, diploid, shallow deletion, or
deep deletion.
.get_TCGA_CNV()a data frame that contains CNV threshold data for all TCGA 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_ratio(),
.get_TCGA_CNV_value(),
.get_TCGA_GTEX_RNAseq(),
.get_TCGA_RNAseq()
if (FALSE) {
.get_TCGA_CNV()
}