Create strain mask

Converts a data frame of individual sampling times to give the index of the last infection that individual could have had

create_strain_mask(titre_dat, strain_isolation_times)

Arguments

titre_dat	the data frame of titre data. See example_titre_dat
strain_isolation_times	the vector of times that individuals can be infected

Value

a vector giving the last index of strain_isolation_times that an individual can be infected