how to add TCGA CNV as covariate for matrixeqtl

Question

[Binghong]

Hi all, I want to add the CNV data from TCGA as a covariate for matrixeqtl, but each sample has many CNVs, which is not the correct format as a covariate for matrixeqtl, how can I make each sample only have one CNV value? Any guidance is appreciated!