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I am trying to create a map that shows diverging values. I tried to set the breaks but somehow the different classes don't show different colours (click here for the map). The output map always has the same colour for several classes.

tm_shape(abm_population)+ tm_fill("diff_rel_growth",breaks=c(min(abm_population$diff_rel_growth,na.rm = T),-0.5,-0.3,-0.1,0.1,0.3,0.5,max(abm_population$diff_rel_growth,na.rm = T)))

What am I missing or doing wrong?

Marco Maurer
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1 Answers1

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It is difficult to privde a full answer given that, even though you provide the code, t is difficult to reproduce your issue.

Neverheless, my feeling is that your code is working properly. It seems like your problem is more related to the way you are defining the classes. Notice that you have one giant category ranging from 0.50 to 61.93 (This category seems the one with more polygons).

One first step is tho double check your data. Then, see if you can define a different set of breaks.

Finally, you can also control the colors:

nc = st_read(system.file("shape/nc.shp", package="sf"))
Breaks <- c(0, 2000, 4000, 6000, 31000)
Labels <- c("0 - 2000", "2000 - 4000", "4000 - 6000", ">6000")
MyPalette <- c("#f2f0f7", "#cbc9e2", "#9e9ac8", "#6a51a3")

tm_shape(nc) + tm_polygons(col="BIR79", title = "Births 1979 - 84", 
                           palette = MyPalette,
                           breaks = Breaks, labels = Labels) + 
tm_layout(legend.position = c(0.01,0.65),
          scale=0.65,
          legend.frame = T,
          bg.color = "lightblue") + 
tm_compass(size = 5, type = "rose", lwd = 3) + 
tm_scale_bar(breaks = c(0,50,100,150,200),size = 1, position = c(0.06,0),
             lwd = 3)
Orlando Sabogal
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  • Thank you. You created an own palette to define the colours. That already solved the problem to the biggest. Now I just need to define them better. The big class from 0.5 to 61.93 is set as such on purpose. The map shows deviations between real and predicted population sizes of a model I created. Therefore, I want to have high differences in the same class. – Marco Maurer Jun 13 '20 at 09:38
  • I am glad it helped you. Please do not forget to mark the question as solved so everybody else can know it. – Orlando Sabogal Jun 13 '20 at 15:46