geom-raster.md
In ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics

geom_raster() checks input and coordinate system

`hjust` must be a number, not a double vector.

`hjust` must be a number, not the string "a".

`vjust` must be a number, not a double vector.

`vjust` must be a number, not the string "a".

Code
  b <- ggplotGrob(p)
Message
  `geom_raster()` only works with linear coordinate systems, not `coord_polar()`.
  i Falling back to drawing as `geom_rect()`.

geom_raster() fails with pattern fills

Problem while converting geom to grob.
i Error occurred in the 1st layer.
Caused by error in `draw_panel()`:
! `geom_raster()` cannot render pattern fills.