dropFirst: Drop the first element of a vector or matrix
Description
A utility function, dropFirst drops the first element of a
vector or matrix, retaining the correct time series attributes, in
case the argument is a time series object.
Usage
dropFirst(x)
Value
The function returns x[-1] or x[-1,], if the argument is
a matrix. For an argument of class ts the class is preserved,
together with the correct tsp attribute.