facet_grid

[danbebber]

I've posted this on Stack Overflow: tidyterra allows use of facet_wrap(~lyr) to plot multiple spatial raster layers in one figure.

library(terra)
library(ggplot2)
library(tidyterra)
x <- rast(array(data = rnorm(120,0,1), dim=c(5,5,4)))
names(x) <- c("A_1", "B_1", "A_2", "B_2")
ggplot() +
  geom_spatraster(data = x) +
  facet_wrap(~lyr)

Is there any way of implementing facet_grid in tidyterra so that, in the case above for example, the rows would be labelled 1 and 2, and columns would be labelled A and B?
This would require a spatraster object to have more than one attribute (the name of the layer) associated with it, I guess. I don't know if a data.frame can be associated with a spatraster object in which each row refers to a layer?

[dieghernan]

Maybe this? fortify to a tibble with tidyterra method, and then pivot, split labels and plot as a regular data frame.

library(terra)
#> terra 1.7.78
library(ggplot2)
library(tidyterra)
#> 
#> Attaching package: 'tidyterra'
#> The following object is masked from 'package:stats':
#> 
#>     filter
x <- rast(array(data = rnorm(120, 0, 1), dim = c(5, 5, 4)))
names(x) <- c("A_1", "B_1", "A_2", "B_2")
ggplot() +
  geom_spatraster(data = x) +
  facet_wrap(~lyr, ncol = 2) +
  coord_sf(crs = pull_crs(x)) +
  labs(x = "", y = "")

# Fortify method converting to data.frame
x_frt <- fortify(x) %>%
  pivot_longer(-c(x:y), names_to = "lyr", values_to = "value") %>%
  mutate(
    col_n = stringr::str_split_i(lyr, "_", 1),
    row_n = stringr::str_split_i(lyr, "_", 2)
  )



x_frt
#> # A tibble: 100 × 6
#>        x     y lyr    value col_n row_n
#>    <dbl> <dbl> <chr>  <dbl> <chr> <chr>
#>  1   0.5   4.5 A_1   -0.318 A     1    
#>  2   0.5   4.5 B_1    1.02  B     1    
#>  3   0.5   4.5 A_2   -0.612 A     2    
#>  4   0.5   4.5 B_2    0.989 B     2    
#>  5   1.5   4.5 A_1   -2.68  A     1    
#>  6   1.5   4.5 B_1    1.83  B     1    
#>  7   1.5   4.5 A_2   -0.792 A     2    
#>  8   1.5   4.5 B_2    0.132 B     2    
#>  9   2.5   4.5 A_1    0.274 A     1    
#> 10   2.5   4.5 B_1    0.128 B     1    
#> # ℹ 90 more rows

ggplot(x_frt, aes(x, y, z = value, fill = value)) +
  geom_raster() +
  facet_grid(vars(row_n), vars(col_n)) +
  coord_sf(crs = pull_crs(x)) +
  labs(x = "", y = "")

^{Created on 2024-07-30 with reprex v2.1.1}

Session info

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