You can first convert the "ATCG" hapmap format of your file to numerical genotypes format in TASSEL. Then simply write an appropriate R scrip to convert into the -1/0/1.

For example, here is how I convert my file from the 0/1/2 to 1/0/-1

file[file== "0"]< - -1

file[file== "1"]

Thank you Admas Alemu. I found out how to change it to -1/0/1 at https://github.com/haktansuren/snp-toolset.

I opened SNP_HapMapToNumeric.pl and found that changing -1/0/1 for hetero and homo changed.

Thanks for your reply.