vec_seq_along() is equivalent to seq_along() but uses size, not length.
vec_init_along() creates a vector of missing values with size matching
an existing object.
Usage
vec_seq_along(x)
vec_init_along(x, y = x)
Value
vec_seq_along() an integer vector with the same size as x.
vec_init_along() a vector with the same type as x and the same size
as y.