Поместите вектор в матрицу из 2 строк и примените функцию toString()
к каждому столбцу.
apply(matrix(x, 2), 2, toString)
# [1] "Joe Exotic, Tiger King, Lead"
# [2] "Carole Baskin, Husband Killer, Tiger Queen"
# [3] "Doc Antle, Tiger Person, Swinger"
Данные
x <- c("Joe Exotic", "Tiger King, Lead", "Carole Baskin", "Husband Killer, Tiger Queen", "Doc Antle", "Tiger Person, Swinger")