Modifying Vcf field into R

I am trying to replace the CHROM and POS of a vcf from this

> NODE_1 56
> NODE_1 456
> NODE_2 45
> NODE_3 111
> NODE_3 211
> NODE_4 78

To this

> Scaffold_10 123556
> Scaffold_10 123956
> Scaffold_7 14575
> Scaffold_8 21457
> Scaffold_8 21557
> Scaffold_2 14569

I wanted to to all this in the R environment. Is there a way?
Thanks to everybody