[R-sig-Geo] putting scalebar and north arrow on google map

[Manuel Spínola]

Or you can try the package ggsn with the package ggmap

Manuel

2016-07-17 22:57 GMT-06:00 Chris Lusk <clusk at waikato.ac.nz>:

> Hi - I've made a map to show the spatial arrangement of my plots, and would
> now like to add a scale bar (in hundreds of metres) and a north arrow. I've
> seen several solutions online, most of which threw error messages when I
> tried them. Although the solution below doesn't give an error message, it
> doesn't actually add anything to the map!
>
> Any advice would be appreciated.
>
> Chris
> ..........
>
> library(ggplot2)
> library(ggmap)
> library(maps)
> library(GISTools)
>
> ##Coordinates of four types of plots
> Gaps <- read.table(text="lon lat
> 176.431823     -38.086894
> 176.4329002     -38.08855667
> 176.4286505     -38.08421246
> 176.4239767     -38.08297953
> 176.4306576     -38.09032491
> 176.4181457     -38.08283416
> 176.4325089     -38.09042394
> 176.4243027     -38.08215021
> 176.4220882     -38.08720573
> 176.430974    -38.093108", header = TRUE, strip.white = TRUE)
>
> Understorey <- read.table(text="lon lat
> 176.431523   -38.086965
> 176.418408   -38.082935
> 176.4244189     -38.08242069
> 176.4287644     -38.08372266
> 176.4240118     -38.0823004
> 176.4333778     -38.08853369
> 176.4217424     -38.0876122
> 176.4309304     -38.09055117
> 176.4324084     -38.0907023
> 176.430821   -38.093687", header = TRUE, strip.white = TRUE)
>
> Treeferns <- read.table(text="lon lat
> 176.432134      -38.086298
> 176.4246547     -38.08226916
> 176.4335132     -38.08801622
> 176.4183628     -38.08260261
> 176.429       -38.08413018
> 176.4213997     -38.08710868
> 176.4304333     -38.09064678
> 176.4324081     -38.0909994
> 176.4242689     -38.08264669
> 176.429837      -38.093061", header = TRUE, strip.white = TRUE)
>
> Margins <- read.table(text="lon lat
> 176.4225302     -38.08177849
> 176.427018     -38.08879161
> 176.4207786     -38.08356826
> 176.4315118     -38.08251629
> 176.426456     -38.08920441
> 176.426010   -38.088253
> 176.422526   -38.082794
> 176.421399   -38.084780
> 176.429339   -38.092742", header = TRUE, strip.white = TRUE)
>
> ## Get the map at right zoom level
> OkatainaMap <- get_googlemap(center = c(lon = 176.425, lat = -38.0845),
> maptype='hybrid', zoom=15)
>
> ## Plot the points on the map
> ggmap(OkatainaMap) +
>   geom_point(data=Gaps, aes(x=lon, y=lat), pch=15, colour="chartreuse1",
> size=2.5, alpha=1) +
>   geom_point(data=Understorey, aes(x=lon, y=lat), pch=21, colour="gray40",
> bg="black", size=3, alpha=1) +
>   geom_point(data=Treeferns, aes(x=lon, y=lat), pch=23, colour="gray40",
> bg="blue", size=2.5, alpha=1) +
>   geom_point(data=Margins, aes(x=lon, y=lat), pch=17, colour="orange",
> size=2.5, alpha=1)
>
> ##Add scale and north arrow (NEITHER COMMAND WORKS FOR ME)
>
> map.scale(x=176.42,y=-38.092, ratio=FALSE, relwidth=0.2, col="white")
> north.arrow(xb=176.435, yb=-38.079, len=0.02, lab="N", col="white")
>
> ...................
>
>
> Dr. Chris Lusk
> Senior Research Fellow
> Environmental Research Institute
> The University of Waikato
> Private Bag 3105, Hamilton
> New Zealand / Aotearoa
> http://sci.waikato.ac.nz/sites/clusk/
> Ph 64 7 838 4205
> Senior Editor, *NZ J Botany*
> ~  ~  ~  ~  ~  ~  ~  ~  ~  ~  ~
>
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>
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>



-- 
*Manuel Spínola, Ph.D.*
Instituto Internacional en Conservación y Manejo de Vida Silvestre
Universidad Nacional
Apartado 1350-3000
Heredia
COSTA RICA
mspinola at una.cr <mspinola at una.ac.cr>
mspinola10 at gmail.com
Teléfono: (506) 8706 - 4662
Personal website: Lobito de río <https://sites.google.com/site/lobitoderio/>
Institutional website: ICOMVIS <http://www.icomvis.una.ac.cr/>

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