如何使用python将Tab-delimited格式的SNP矩阵转换为数字？

I am attempting to transform the bases in the tab-delimited file into integers. The input file must be duplicated and the new copy must have a '1' for the reference base and a '2' for the most common alternate allele after that, and a '3' for for the next and so on. I'm new to python so any help is welcome, i've been attempting to use pandas because the file is so large. Here is a sample of the data:I am attempting to transform the bases in the t