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I wanted to make a simple plot of four sf-objects which don't contain much more than the sfc-column and some postal-code information.

The sf-objects have the names level 1-4 and plz. What I would like to have is a simple legend next to my map just showing the names of the objects (level 1-4) and plz and their matching colours.

It seems like a task which would be so easy in any desktop-gis, but I'd really like to do it in R. My code so far looks like this and produced the follwing figure.

ggplot() +
  geom_sf(data = level3, fill = fil.a) +
  geom_sf(data = level2, fill = fil.b) +
  geom_sf(data = level1, fill = fil.c) +
  geom_sf(data = plz, fill = "red") +
  coord_sf()

enter image description here

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you have to pass the parameter "show.legend = 'polygon'" to geom_sf(); since you are not "mapping" a variable to the polygon's fill, but using 4 geom_sf() calls, you have to adjust scale_fill_manual to refer to the colors and polygons, first referring them on the geom_sf call:

geom_sf(data = level3, aes(fill = "A"), alpha = .5, 
          show.legend = "polygon", inherit.aes = F) +
geom_sf(data = level2, aes(fill = "B"), alpha = .5, 
          show.legend = "polygon", inherit.aes = F) +
scale_fill_manual(values = c("A" = "red", "B" = "green"), 
                    labels = c("level3", "level2"), name = "the_levels")
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    thanks a lot!! I'll give it a shot tomorrow!
    – Lenn
    Nov 21 '19 at 22:35
  • thanks a lot:) It worked pretty good. But do you have any idea, how I could add another layer with the legend-label depending on one of the column-names. In this case the plz-layer has a column labeled plz. And I would like to add "plz" to my legend.
    – Lenn
    Nov 22 '19 at 8:57
  • the way ggplot works is mapping variables to geoms, if you want to see a legend with plz values you should map it to aes(fill = plz), it may be good if you convert it to character or factor (i'm guessing it's postleitzahl), otherwise ggplot will use a continuous scale with min and max values
    – Elio Diaz
    Nov 22 '19 at 16:04
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    thanks a lot! Helped a lot again. I hope in some time I can also give some helpful advices here
    – Lenn
    Nov 23 '19 at 7:09

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