rggplot2mappingshapefile

ggplot Bathymetric shapefile plotting in a single colour

I have a bathymetric shapefile structured as below.

str(Ab_bath)
Classes ‘sf’ and 'data.frame':  126 obs. of  13 variables:
 $ CLRRGB  : chr  "2844D9FF" "2651DCFF" "215DDEFF" "2266E0FF" ...
 $ COLOR   : int  85 91 91 91 91 55 98 62 62 62 ...
 $ LAYER   : int  30 30 30 30 30 30 30 30 30 30 ...
 $ L_LIMIT : int  0 0 0 0 0 0 0 0 0 0 ...
 $ MAJ_CAT : chr  "Nautical" "Nautical" "Nautical" "Nautical" ...
 $ MAX_ELEV: num  -14.8 -14.5 -14.2 -14 -13.8 ...
 $ MIN_CAT : chr  "Depth Area" "Depth Area" "Depth Area" "Depth Area" ...
 $ MIN_ELEV: num  -15 -14.8 -14.5 -14.2 -14 ...
 $ MODE    : chr  "D_MR" "D_MR" "D_MR" "D_MR" ...
 $ VALUE   : chr  "14.75" "14.5" "14.25" "14" ...
 $ VALUE2  : chr  "15" "14.75" "14.5" "14.25" ...
 $ U_LIMIT : int  8 8 8 8 8 8 8 8 8 8 ...
 $ geometry:sfc_MULTIPOLYGON of length 126; first list element: List of 2
  ..$ :List of 2
  .. ..$ : num [1:3358, 1:2] 0.887 0.887 0.887 0.887 0.887 ...
  .. ..$ : num [1:2678, 1:2] 0.888 0.888 0.888 0.888 0.888 ...
  ..$ :List of 2
  .. ..$ : num [1:1342, 1:2] 0.886 0.886 0.886 0.886 0.886 ...
  .. ..$ : num [1:1049, 1:2] 0.886 0.886 0.886 0.886 0.886 ...
  ..- attr(*, "class")= chr [1:3] "XY" "MULTIPOLYGON" "sfg"
 - attr(*, "sf_column")= chr "geometry"
 - attr(*, "agr")= Factor w/ 3 levels "constant","aggregate",..: NA NA NA NA NA NA NA NA NA NA ...
  ..- attr(*, "names")= chr [1:12] "CLRRGB" "COLOR" "LAYER" "L_LIMIT" ...

I was able to plot it simply using the code below

ggplot() +
  geom_sf(data = Ab_bath_utm, fill = "lightblue", color = "blue", alpha = 0.5)+
  coord_sf(datum = 32631) #makes axes in UTM

first working plot

I thought I'd try and scale the colour by min elevation using this code

ggplot() +
  geom_sf(data = Ab_bath_utm, aes(fill = MIN_ELEV), color = "black", size = 0.1) +
  scale_fill_gradientn(
    colors = c("navy", "blue", "lightblue", "white"),
    name = "Min Elevation (m)"
  ) +
  coord_sf(datum = 32631) +
  theme_minimal()

But it just plots a single colour. How can I get it to plot a scale of colours by elevation? A link to the shapefile can be found here

second one color plot

Solution

  • Very weird, this one took me a while. @JonSpring hit the nail on the head! The problem lies within the last 5 polygones which indeed overlap all previous ones. You can see that, if you run:

    plot(st_geometry(Ab_bath_utm[126,]))

    this is shown

    So you can sort in ascending order by MIN_ELEV and this will fix your issue

    library(sf)
library(ggplot2)
Ab_bath_utm <- st_read("D_Areas.shp")
Ab_bath_utm <- Ab_bath_utm[order(Ab_bath_utm$MIN_ELEV), ] # resort

ggplot() +
  geom_sf(data = Ab_bath_utm, aes(fill = MIN_ELEV), color = "black", lwd = 0.001) +
  scale_fill_gradientn(colors = c("navy", "blue", "lightblue", "white"),name = "Min Elevation (m)") +
  coord_sf(datum = 32631) + theme_minimal()

    out