adding a scale

 Not to bad hint :p

So From this one, I modified the function to get it work correctly:

#############################################################################################################################################################################
####                                                                                     Scale                                                                                               ####
#############################################################################################################################################################################

scalebar <- function(loc,length,unit="km" ,degrees = TRUE,cex=par("cex"), ...) {
        if(missing(loc)) stop("loc is missing")
        if(missing(length)) stop("length is missing")
        z <- c(0,length/c(4,2,4/3,1),length*1.1)+loc[1]
        if(degrees == TRUE) length<-180*(acos((cos(length/6371)-sin(loc[2]*pi/180)*sin(loc[2]*pi/180))/(cos(loc[2]*pi/180)*cos(loc[2]*pi/180))))/pi
        x <- c(0,length/c(4,2,4/3,1),length*1.1)+loc[1]
        y <- c(0,length/(10*3:1))+loc[2]
        cols <- rep(c("black","white"),2)
        for (i in 1:4) rect(x[i],y[1],x[i+1],y[2],col=cols[i])
         for (i in 1:5) segments(x[i],y[2],x[i],y[3])
         labels <- z[c(1,3)]-loc[1]
labels <- append(labels,paste(z[5]-loc[1],unit))
text(x[c(1,3,5)],y[4],labels=labels,cex,pos=3,offset=0) }


and pushed it in my package https://github.com/giby/Linarius if someone wanna try. I could do some improve to support other units, I'll do that latter on.

Thanks a lot for help

Benjamin

On Saturday, April 25, 2015 10:36 GMT, Guido Schulz <gosz at gmx.de> wrote:

You may want to check out this paper "Auxiliary Cartographic Functions
in R: North Arrow, Scale Bar, and Label with a Leader Arrow"
(http://www.jstatsoft.org/v19/c01/paper).

It provides functions to add arrow and scale bar for plot.


Am 24.04.2015 um 14:10 schrieb Gilles Benjamin Leduc:

Hi again, > > So, I use the plot() function. > I read a shapefile, that I convert in GPS coordinates like this: > > readOGR(dsn=S50V_STRANDLINA_24122014_ISN2004/IS50V_STRANDLINA_SHP", layer="is50v_strandlina_flakar_24122014")->IslHD
spTransform(IslHD,CRS(" +proj=nglat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 "))->IslHD > > then plot : plot(IslHD) > > I tried several stuff for making a scale, results were either ugly or wrong? > The function Scalebar make a cute scale but really absurd? > > Any idea? > > Best regards

Benjamin   >  >  > On Thursday, April 23, 2015 05:18 GMT, Frede Aakmann T?gersen <frtog at vestas.com> wrote: >  >> Hi Benjamin

Yes, there are several ways to do that. But it depends on which kind of plotting function you used. Usually it is a setting of an argument of the plotting function.

I cannot help you more since I don't more than the information you provided in your email.

If you want more help from this list please provide a small example showing which functions you used with information on which package(s) they belong. Then you'll probably get more help.

The small example you can probably find in the example section on the help page for the plotting function.

Best Regards

Frede Aakmann T?gersen
Specialist, M.Sc., Ph.D.
Plant Performance & Modeling

Technology & Service Solutions
T +45 9730 5135
M +45 2547 6050
frtog at vestas.com
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-----Original Message-----
From: R-sig-Geo [mailto:r-sig-geo-bounces at r-project.org] On Behalf Of Gilles Benjamin Leduc
Sent: 23. april 2015 02:46
To: r-sig-geo at r-project.org
Subject: [R-sig-Geo] adding a scale

Hi all,

I am ploting map from shapefiles (curently read with readOGR from rgdal). >> My PhD supervisor asked me to add a scale? Before going in crazy computation and the arrow function I wonder? Is there a function that can do it automatically (or easily) >>
Thanks in advance >>
Benjamin