I have a simple RasterLayer in R. I added a column to the attribute table and would like to use these values in the legend of my leaflet-map. The RasterLayer looks like this:

> layer1
class      : RasterLayer 
dimensions : 38, 40, 1520  (nrow, ncol, ncell)
resolution : 1000, 1000  (x, y)
extent     : 4303000, 4343000, 3365000, 3403000  (xmin, xmax, ymin, ymax)
crs        : +proj=laea +lat_0=52 +lon_0=10 +x_0=4321000 +y_0=3210000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs 
source     : memory
names      : ue65 
values     : 1, 5  (min, max)
attributes :
 ID VALUE percentage
  1     1          0
  2     2       0-15
  3     3      15-20
  4     4      20-25
  5     5        >25

And the code for making the leaflet map like this:

leaflet() %>%
  addProviderTiles('Esri.WorldImagery',group='Imagery') %>%
  addProviderTiles('Esri.WorldStreetMap', group='Streets') %>%
  addRasterImage(layer1, colors = pal, opacity = 0.7, group = "layer1") %>%
    baseGroups = c("Imagery", "Streets"),
    overlayGroups = c("layer1"),
    options = layersControlOptions(collapsed = FALSE)
  ) %>%
  addLegend(pal = pal, values = values(layer1$percentage))

I just cant figure out how to use the percentage-column from the attributes table in my legend. If I use: values = values(layer1) it shows 1-5 in the legend. Any hint would be superhelpfull!!


This works for me. Note how to get the names from the percentage column of the first set of levels of the raster, and I had to use colors= instead of pal= in addLegend, and made the pal object with pal=rainbow(5):

leaflet() %>%
 addProviderTiles('Esri.WorldImagery',group='Imagery') %>%
 addRasterImage(layer1, colors = pal, opacity = 0.7, group = "layer1") %>% 

enter image description here

| improve this answer | |
  • thanks a lot for the quick answer! Don't know how you guys can solve these things so quickly. Anyways: Thanks a lot:) – LeKo Nov 30 '19 at 14:03
  • Would have been quicker if I hadn't had to make a sample raster! I've just been teaching R/geospatial so this is all fresh in my head. And answering Qs here keeps it fresh. – Spacedman Nov 30 '19 at 14:16
  • thanks a lot!! I hope that some day I'll also be able to answer questions and not only post a lot of questions. Do you maybe have any hint for a good ressource (I'm currently reading the Geocomputation with R and super liking it) for R/geospatial topics? – LeKo Nov 30 '19 at 14:44

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