The two most important arguments to this function are X, which specifies a vector containing the data, and FUN, which specifies the name of a function that should be applied to each element of the dat...The two most important arguments to this function are X, which specifies a vector containing the data, and FUN, which specifies the name of a function that should be applied to each element of the data vector. Each such value defines a group: the tapply() function constructs the subset of X that corresponds to that group, and then applies the function FUN to that subset of the data.
