Repository files navigation

Quiver plots for ggplot2. An extension of ‘ggplot2’ to provide quiverplots to visualise vector fields. This functionality is implementedusing a geom to produce a new graphical layer, which allows aestheticoptions. This layer can be overlaid on a map to improve visualisation ofmapped data.

Thestable version can be installed from CRAN:

install.packages("ggquiver")

Thedevelopment version can be installed from GitHub using:

# install.packages("remotes")remotes::install_github("mitchelloharawild/ggquiver")

ggquiver introduces a new geomgeom_quiver(), which produces aquiver plot inggplot2.

Quiver plots for functions can easily be produced using ggplotaeshetics. When a grid is detected, the size of the vectors areautomatically adjusted to fit within the grid.

library(ggplot2)library(ggquiver)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()

Theggplot2 example for seal movements is easily reproduced, withappropriately scaled arrowhead sizes. Here, the vecsize is set to zeroto not resize the vectors.

library(maps)world<-sf::st_as_sf(map('world',plot=FALSE,fill=TRUE))ggplot(seals)+   geom_quiver(    aes(x=long,y=lat,u=delta_long,v=delta_lat),vecsize=0  )+   geom_sf(data=world)+  coord_sf(xlim= c(-173.8,-117.8),ylim= c(28.7,50.7),expand=FALSE)+   labs(title="Seal movements",x=NULL,y=NULL)

Quiver plot arrows can be centered about x and y coordinates, which isuseful when working with maps and scaled vectors.

ggplot(seals)+   geom_quiver(    aes(x=long,y=lat,u=delta_long,v=delta_lat),vecsize=0,center=TRUE  )+   geom_sf(data=world)+  coord_sf(xlim= c(-173.8,-117.8),ylim= c(28.7,50.7),expand=FALSE)+   labs(title="Seal movements (centered arrows)",x=NULL,y=NULL)