Extract, replace, reorder MS
Treat multiple sequences as a array where each row corresponds to a sequence for one species.
## S3 method for class 'ms' x[rows]
An object of type
A numeric vector of sequence indices,
character vector (containing sequence name), or
logical vector (containing sequences to keep). If logical vector it
will be recycled as necessary to the same length as
The bracket notation can return a set of sequences, or re-order rows.
An MS object sampled from x as indicated by rows.
This function will not alter the value of x even if it is stored as a pointer to a C structure.