[R-sig-Geo] adding a scale

[Roger Bivand]

On Fri, 24 Apr 2015, Gilles Benjamin Leduc wrote:

> Here i a minimal exemple:
>
> #Get data
> data(state)
> states <- data.frame(state.x77, state.center)
> states <- states[states$x > -121,]
> coordinates(states) <- c("x", "y")
> proj4string(states) <- CRS("+proj=longlat +ellps=clrk66")
> #Put in my system
> spTransform(states,CRS(" +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 "))->states
> #plot it
> plot(states,axes = TRUE)

library(sp)
library(rgdal)
data(state)
states <- data.frame(state.x77, state.center)
states <- states[states$x > -121,]
coordinates(states) <- c("x", "y")
proj4string(states) <- CRS("+proj=longlat +ellps=clrk66")
states <- spTransform(states, CRS(" +proj=longlat +datum=WGS84 +no_defs
  +ellps=WGS84 +towgs84=0,0,0 ")) # no-op at this scale
plot(states, axes = TRUE) # scale information provided

but it isn't either easy or logical to include a metric scale, as a 1cm 
line will represent (very) different lengths at the north and south of the 
figure. North is upwards, but if you want a North arrow too, you get it 
with this (clicking to place the symbol):

SpatialPolygonsRescale(layout.north.arrow(), offset=locator(1), scale=3, 
plot.grid=FALSE)

states <- spTransform(states, CRS("+init=epsg:2163"))
plot(states, axes=TRUE)
SpatialPolygonsRescale(layout.north.arrow(), offset=locator(1), 
scale=4e+5, plot.grid=FALSE)
SpatialPolygonsRescale(layout.scale.bar(), offset=locator(1), 
scale=500000, fill=c("transparent", "black"), plot.grid=FALSE)
text(locator(1), "0")
text(locator(1), "500 km")

is at least not stupid, even if not shiny graphically. They are, however, 
redundant as information, as all that is needed is in the axes.

Roger

>
> How to add a scale on it… the function spplot do not work with my shapefile.
>
> Benjamin
>
>
> On Friday, April 24, 2015 12:32 GMT, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>
>> On Fri, 24 Apr 2015, Gilles Benjamin Leduc wrote:
>>
>>> Hi again,
>>>
>>> So, I use the plot() function.
>>> I read a shapefile, that I convert in GPS coordinates like this:
>>
>> Please do provide a reproducible example. When you have a working
>> reproducible example, you'll find that you have solved your problem. Note
>> that right-assignment is confusing. Have you consulted the R spatial
>> graphics gallery:
>>
>> http://rspatial.r-forge.r-project.org/gallery/
>>
>> Further note that metric scales are hard to get right on maps in degrees.
>> Usually, the inclusion of annotated axes is a rational substitute for a
>> scale bar, and by default the vertical axis is the same as the North
>> arrow, which is only really needed when vertical is not North.
>>
>> Roger
>>
>>>
>>> readOGR(dsn="IS50V_STRANDLINA_24122014_ISN2004/IS50V_STRANDLINA_SHP", layer="is50v_strandlina_flakar_24122014")->IslHD
>>> spTransform(IslHD,CRS(" +proj=longlat +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 Tøgersen <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 Tøgersen
>>>> Specialist, M.Sc., Ph.D.
>>>> Plant Performance & Modeling
>>>>
>>>> Technology & Service Solutions
>>>> T +45 9730 5135
>>>> M +45 2547 6050
>>>> frtog at vestas.com
>>>> http://www.vestas.com
>>>>
>>>> Company reg. name: Vestas Wind Systems A/S
>>>> This e-mail is subject to our e-mail disclaimer statement.
>>>> Please refer to www.vestas.com/legal/notice
>>>> If you have received this e-mail in error please contact the sender.
>>>
>>>>
>>>> -----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
>>>>
>>>> _______________________________________________
>>>> R-sig-Geo mailing list
>>>> R-sig-Geo at r-project.org
>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo at r-project.org
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>> --
>> Roger Bivand
>> Department of Economics, Norwegian School of Economics,
>> Helleveien 30, N-5045 Bergen, Norway.
>> voice: +47 55 95 93 55; fax +47 55 95 91 00
>> e-mail: Roger.Bivand at nhh.no
>
>
>
>

-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: Roger.Bivand at nhh.no