mitchelloharawild / ggquiver Goto Github PK

I want to create a plot with geom_quiver() and underlie a map. This works in the given example, when using borders():

# Removing automatic scaling
ggplot(seals, aes(x=long, y=lat, u=delta_long, v=delta_lat)) +
  geom_quiver(vecsize=NULL) +
  borders("state")

but, I want to plot something similar using geom_sf() instead:

library(maps); library(sf)
#> Linking to GEOS 3.8.0, GDAL 3.0.4, PROJ 6.3.1
states <- sf::st_as_sf(map('usa', plot = FALSE, fill = TRUE))
ggplot() + geom_quiver(data=seals, aes(x=long, y=lat, u=delta_long, v=delta_lat), vecsize=NULL) + 
  geom_sf(data = states)
#> Error: $ operator is invalid for atomic vectors

Unfortunately, this throws up an error: $ operator is invalid for atomic vectors

I just encountered this case, it seems geom_quiver does not check if the dimensions are equal between X and Y. This causes a problem that the directions of the arrows do not correct. This is easily fixable by using coord_equal or coord_fixed but it might be good to warn users to do so. Maybe it can be checked if the coord inherits CoordFixed, maybe a check for the ratio would also be good? (The first plot is incorrect)

d<-data.frame(t=Sys.time()+(3600*1:4), x=1000*c(1,-1), y=1000*c(1,1,-1,-1))
require(ggplot2)
#> Loading required package: ggplot2
require(ggquiver)
#> Loading required package: ggquiver
ggplot(d)+geom_quiver(aes(x=t, y=0, u=y,v=x))

ggplot(d)+geom_quiver(aes(x=t, y=0, u=y,v=x))+coord_equal()

^{Created on 2022-03-07 by the reprex package (v2.0.1)}

Hi!
Thanks for this great package. geom_quiver() is returning the following warning (with no output) when I try to reproduce the examples in the package:

Warning message:
Computation failed in `stat_quiver()`:
argument is of length zero 

I noticed the pkgdown documentation is showing the same error.

Reprex:

library(ggplot2)
library(ggquiver)
library(dplyr)

expand.grid(x=seq(0,pi,pi/12), y=seq(0,pi,pi/12)) %>%
  ggplot(aes(x=x,y=y,u=cos(x),v=sin(y))) +
  geom_quiver()

Thanks!

Automatic grid setup with function inputs

https://github.com/teunbrand/ggarrow

Hi,
I've tried to overlay arrows to a basemap as in this example:

library(ggmap)
library(dplyr)

wind_data <- wind %>% filter(between(lon, -96, -93) & between(lat, 28.7, 30))
qmplot(lon, lat, data=wind_data, extent="panel", geom = "blank", zoom=8, maptype = "toner-lite") +
geom_quiver(aes(u=delta_lon, v=delta_lat, colour = spd), center=TRUE)

but only the base map and the color scale are showing.
geom_quiver still works when overlaid on ggplot.

packageVersion('ggplot2') ‘3.3.5’
packageVersion('ggmap') ‘3.0.0’
packageVersion('ggquiver') ‘0.2.0’
platform x86_64-pc-linux-gnu
version.string R version 3.6.3 (2020-02-29)

Would it be something I need to update?

Thanks!