the first year, vector of years, matrix, or data frame.
y
the last year, if x is only the first year.
Value
A string of the form "1990-2000".
Details
If x is a vector or a data frame, then the lowest and highest years
are used, and y is ignored.
If x is a matrix or data frame, this function looks for years in the
first column. If the values of the first column do not look like years (four
digits), then it looks for years in the row names.
See Also
paste is the underlying function to paste strings.