

   PPlloott JJaappaann''ss CCooaasstt LLiinnee aanndd PPrreeffeeccttuurreess

        jpn(region, xlim = c(128, 147), ylim = c(29.6, 47), pref = T,
            coast = T, add = F, okinawa = T, ar = 4/5, eps = 0.25, ...)

   AArrgguummeennttss::

     region: region which should be drawn.  A list containing
             components named `x' and `y' or a list of such
             objects.  If missing, `xlim' and `ylim' are used.

       xlim: optional limits for the x-axis (longitude).  The
             longitude for Okinawa is different from the real
             one.  See argument `okinawa'.

       ylim: optional limits for the y-axis (latitude).  The
             latitude for Okinawa is different from the real
             one.  See argument `okinawa'.

       pref: logical flag to control whether prefecture bound-
             aries are plotted or not.

      coast: logical flag to control whether coast-line is
             plotted or not.

        add: logical flag. If TRUE, plot is superimposed on
             existing plot.  Otherwise, a new plot is gener-
             ated.

    okinawa: logical flag.  Okinawa is drawn in the box placed
             on the Japan sea.  To put points or draw texts
             around Okinawa, shift longitude by
             +3.7767(degrees) and latitude by
             +13.05505(degrees).

         ar: aspect ratio of `longitude' to `latitude'.

        eps: If `region' is given, it is enlarged four ways by
             this amout(degrees).

        ...: optional arguments which will be passed through
             `lines'.

             Graphical parameters (see `par()') may also be
             supplied as arguments to this function.

   EExxaammpplleess::

        ## Region which includes Aomori and Osaka
        jpn(list(jcity$aomori, jcity$osaka), eps = 0.7)
        ## Around Fukuoka
        jpn(jcity$fukuoka, eps = 1)
        ## Shikoku Island
        jpn(xlim = c(132, 135), ylim = c(32.5, 34.5))

