ggplot2 version 3 seems to have an incompatibility with ggmap when using the geom_density2d() function to add a layer. The following code returns an error (though worked with ggplot2 version 2):
# Load libraries
library(ggplot2) # version 3
library(ggmap) # needs to be *dev* version, that's the issue
# Create a data frame
df <- data.frame(
long = rnorm(50, -122.32, .2),
lat = rnorm(50, 47.6, .2)
)
# Use qmplot to create a base layer of map tiles
base_plot <- qmplot(
data = df,
x = long, # data feature for longitude
y = lat, # data feature for latitude
geom = "blank", # don't display data points (yet)
maptype = "toner-background", # map tiles to query
darken = .7, # darken the map tiles
legend = "topleft" # location of legend on page
)
# Show the map in RStudio
base_plot
# Use ggplot to create a 2d density map (without tiles -- works fine)
ggplot(df, aes(x = long, y = lat)) +
geom_density2d() +
stat_density_2d(
aes(x = long, y = lat, fill = stat(level)), # in v2, fill = ..level..
# Use the computed density to set the fill
alpha = .3,
geom="polygon" # Set the alpha (transparency)
)
# Add 2d density plot on map tiles -- returns an error
base_plot +
geom_density2d() +
stat_density_2d(
aes(x = long, y = lat, fill = stat(level)), # in v2, fill = ..level..
# Use the computed density to set the fill
alpha = .3,
geom="polygon" # Set the alpha (transparency)
)
# Error in width_cm(guide$barwidth %||% theme$legend.key.width) :
# Unknown input
Any guidance on how to use geom_density2d() to add a layer to a qmplot() map would be appreciated!
(Map below of the image created with ggplot2 version 2)
> # legend example
> df$class <- factor(sample(0:1, .5*n^2, replace = TRUE))
> p <- qplot(x, y, data = df, geom = "tile", fill = class)
> p
> p + theme_nothing()
> Warning: `panel.margin` is deprecated. Please use `panel.spacing` property instead
> p + theme_nothing(legend = TRUE)
Warning: `panel.margin` is deprecated. Please use `panel.spacing` property instead
Theme element panel.border missing
Theme element axis.line.x.bottom missing
Theme element axis.ticks.x.bottom missing
Theme element axis.line.y.left missing
Theme element axis.ticks.y.left missing
Error in UseMethod("element_grob") :
no applicable method for 'element_grob' applied to an object of class "NULL"
Calls: <Anonymous> ... guide_gengrob.legend -> ggname -> grobName -> element_grob
Execution halted
```
Thanks much, @mara! Someone on SO noted that the issue was just needing to use the development version of ggmap. I can take this post down if it isn't helpful to keep around.
Glad you got there! This is why full reprexes are so helpful for troubleshooting — we have the CRAN packages that have errors, etc. from revdepchecks, so it's a super helpful way to see where the errors are coming from.
Thanks for keeping this post up folks, I ran into a similar issue re-running code with ggmap and the new ggplot2 v3.0 -- this post saved me from a Friday afternoon hole .
hole .