Hi@akhtar,
You can use the select method to extract any columns from a data frame. I have attached one example below for your reference.
> df
  IND snp1 snp2 snp3 snp4 snp5
1   1  A/G  T/T  T/C  G/C  G/G
2   2  A/A  C/C  G/G  G/G  A/A
3   3  T/T  G/G  C/C  C/C  T/T
This is a data frame that has six columns. Now to extract particular columns we can use the select method.
> select(df, snp1,snp3,snp4)
  snp1 snp3 snp4
1  A/G  T/C  G/C
2  A/A  G/G  G/G
3  T/T  C/C  C/C