strip positions in alignment

Question

[mariya_s]

Hi all,

I have a multiple alignment (nucleotide) and I need to strip specific positions from it (drug resistance positions). Do you have any tips where I should start? Obviously, I would like to use R. Please help me with any ideas. Im new to R.

Thank a lot and care care!

[zx8754]

Provide example input and expected output. I am guessing you need substring().