Thanks Barry
all the best.

2011/5/6 Barry Rowlingson <b.rowlingson@lancaster.ac.uk>

> On Fri, May 6, 2011 at 11:56 AM, 王国成 <wangguocheng1986@gmail.com> wrote:
> > Hi, all
> > I recently have a problem about Chinese map drawing. The original code as
> > follows:
> >
> > *library(maps)
> > library(mapdata)
> > map('china')*
> >
> > This is a China map with provincial boundaries. First, how to change the
> > boundaries into dashed lines? Second, how to combine two regions (like
> Xin
> > Jiang and Tibet) together and create a new bold boundary of this new
> region
> > combined by Xin Jiang and Tibet?
>
>  ?map says:
>
>     ...: Extra arguments passed to ‘polygon’ or ‘lines’.
>
>  and if you read ?lines and ?polygon you'll see that dashed lines can
> be drawn using the lty parameter.
>
> map("china",lty=2) will get you dashed lines.
>
>  Your second question is a bit harder. The china data in the mapdata
> package seems to not have the region names, and merging regions from
> maps package data format might be a bit tricky.
>
>  Try getting China map data in shapefile or RData format from
> www.gadm.org - then you can merge areas using some of the functions of
> the sp package, or you can do it interactively using a GIS - I
> recommend Quantum GIS as a free, open-source package which can do this
> kind of editing very easily.
>
> Barry
>

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