Running examples in ‘isoband-Ex.R’ failed
The error most likely occurred in:

> base::assign(".ptime", proc.time(), pos = "CheckExEnv")
> ### Name: iso_to_sfg
> ### Title: Convert isolines or isobands to sfg object
> ### Aliases: iso_to_sfg
> 
> ### ** Examples
> 
> if (requireNamespace("sf", quietly = TRUE)) {
+ library(sf)
+ library(ggplot2)
+ 
+ # Example 1: simple 5x5 matrix
+ m <- matrix(c(0, 2, 2, 2, 0,
+               0, 1, 0, 1, 0,
+               0, 1, 0, 0, 0,
+               0, 1, 0, 1, 0,
+               0, 0, 0, 0, 0), 5, 5, byrow = TRUE)
+ 
+ z <- isolines(1:ncol(m), nrow(m):1, m, c(0.5, 1.5))
+ lines <- iso_to_sfg(z)
+ x <- st_sf(level = names(lines), geometry = st_sfc(lines))
+ ggplot(x) + geom_sf(aes(color = level))
+ 
+ # Example 2: volcano dataset
+ m <- volcano
+ b <- isobands((1:ncol(m))/(ncol(m)+1), (nrow(m):1)/(nrow(m)+1), m,
+               10*9:19, 10*10:20)
+ bands <- iso_to_sfg(b)
+ x <- st_sf(level = as.numeric(sub(":.*", "", names(bands))), geometry = st_sfc(bands))
+ ggplot(x) + geom_sf(aes(color = level, fill = level))
+ 
+ # Example 3: invalid simple features
+ m <- matrix(c(1.5, 1.5, 1.5, 1.5, 0.6,
+               0.5, 1.5, 1.5,   0,   0,
+                 0,   1,   0,   1,   1,
+                 0,   1,   0, 0.7,   0,
+               0.9, 1.3, 1.8, 1.4, 0.4), 5, 5, byrow = TRUE)
+ 
+ raw <- isobands(1:5, 5:1, m, levels_low = 0:1, levels_high = 1:2)
+ bands <- iso_to_sfg(raw)
+ 
+ iso <- st_sf(
+   id = factor(1:length(bands)),
+   geometry = st_sfc(bands)
+ )
+ 
+ # the geometries are not valid
+ st_is_valid(iso, reason = TRUE)
+ # this doesn't prevent us from plotting them
+ ggplot(iso, aes(fill = id)) + geom_sf()
+ 
+ # make all geometries valid, requires GEOS >= 3.8.0
+ if (sf_extSoftVersion()["GEOS"] >= "3.8.0") {
+   iso2 <- st_make_valid(iso)
+   st_is_valid(iso2, reason=TRUE)
+   # the plot should be unchanged
+   ggplot(iso2, aes(fill = id)) + geom_sf()
+ }
+ 
+ # alternatively, if we shift all data values by a tiny
+ # amount (here, 1e-10) so they don't coincide with the band
+ # limits, no invalid geometries are generated.
+ raw <- isobands(1:5, 5:1, m + 1e-10, levels_low = 0:1, levels_high = 1:2)
+ bands <- iso_to_sfg(raw)
+ iso <- st_sf(id = factor(1:length(bands)), geometry = st_sfc(bands))
+ st_is_valid(iso, reason = TRUE)
+ }
Linking to GEOS 3.12.1, GDAL 3.9.0, PROJ 9.4.1; sf_use_s2() is TRUE
Error in library(ggplot2) : there is no package called ‘ggplot2’
Execution halted