[RS-ecology] ADDING SCALE BAR AND CUSTOM COLOURS IN ggplot2

[Brent Thorne]

For the scale bar I would recommended the `ggspatial` package available on CRAN<https://cran.r-project.org/web/packages/ggspatial/index.html> or on github<https://github.com/paleolimbot/ggspatial>. It has automatically applied spatially aware scalebars with only a simple `annotation_scalebar()+` needed.  There are also other nice cartographic options available in this package like vectorized north arrows, where `ggsn` uses a png file for its north arrow options which is not ideal for scaling. Here is the ReadMe<https://github.com/paleolimbot/ggspatial/blob/master/README.md> documentation from GitHub.

W. Brent Thorne, BSc
Master of Science Candidate
Brock University | Department of Earth Sciences
Niagara Region | 1812 Sir Isaac Brock Way | St. Catharines, Ontario, L2S 3A1

________________________________
From: RS-ecology <rs-ecology-bounces at lists.uni-wuerzburg.de> on behalf of Benjamin Leutner <benjamin.leutner at uni-wuerzburg.de>
Sent: Wednesday, July 11, 2018 7:12:47 AM
To: rs-ecology at lists.uni-wuerzburg.de
Subject: Re: [RS-ecology] ADDING SCALE BAR AND CUSTOM COLOURS IN ggplot2

You're close. You need to use scale_fill_manual()
## Example (custom scale and NA handling):
data(lsat)
lsat[1:10,] <- NA ## add some NAs
usc <- unsuperClass(lsat,nClasses=2)
ggR(usc$map, geom_raster = TRUE, forceCat = TRUE) +
        scale_fill_manual(values=c("red", "green"),  na.translate = FALSE)


## Scalebar:
Here's what I use for local projected coordinate systems (e.g. UTM)
Neither pretty, nor smart, but it does exactly that: a simple scalebar

https://gist.github.com/bleutner/08fb0a5a893552b4413bbe02930f722d

For more involved options have a look at the "ggsn" package (I'm not familiar with it, though)



On 10.07.2018 19:54, Rop Willy wrote:

Hi,

The book is awesome and very helpful. I am doing practice and now in Chapter 8. The code runs very well but I have three questions concerning the final map produced:

  1.  When I plot the classification map using ggplot2 I’d like to use my own color scheme but don’t know how. I’ve tried using scale_colour_manual () from the ggplot2 package as well as scalebar() from ggsn package but haven’t really been successful. The code I used is as follows:


// Used ggR() to plot the map

map <- ggR(p224r63_2011_uc$map, geom_raster = TRUE)

// Then used custom theme elements to add other features

map + scale_x_continuous(expand = c(0, 0)) + scale_y_continuous(expand = c(0, 0)) + labs(x = NULL, y = NULL) + theme(axis.text.x = element_text(colour = "grey40", size = 6), axis.text.y = element_text(colour = "grey40", size = 6, angle = 90, hjust = 0.5), legend.text = element_text(colour = "grey10", size = 6), legend.title = element_text(colour = "grey10", size = 8, face = "bold"), axis.ticks = element_line(colour = "grey40"))


How can I change the color scheme manually in ggplot2 instead of using RColorBrewer and other palettes? NB: I’ve tried most options from Stack Overflow and other references but nothing seems to work for me.

  1.  How do I set a simple scale bar like the one used in the book and/or the variant of it in ggplot2?

  2.  When I plot the map for the unsupervised classification (again in ggplot2) there’s a class called NA ( I suppose from unclassified pixels) that appear grey on the legend. Should it be there or should I remove it? If it is not necessary, how is it removed from the final map presentation?

Regards

​



_______________________________________________
RS-ecology mailing list
RS-ecology at lists.uni-wuerzburg.de<mailto:RS-ecology at lists.uni-wuerzburg.de>
https://lists.uni-wuerzburg.de/mailman/listinfo/rs-ecology



--
Benjamin Leutner

Department of Remote Sensing
University of Wuerzburg
Campus Hubland Nord 86
97074 Wuerzburg, Germany

Tel: +49-(0)931-31 89594
Email: benjamin.leutner at uni-wuerzburg.de<mailto:benjamin.leutner at uni-wuerzburg.de>
Web: http://www.fernerkundung.uni-wuerzburg.de

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.uni-wuerzburg.de/pipermail/rs-ecology/attachments/20180711/b8f60a80/attachment-0001.html>