tm_rgb() returns "Error: palette should be a character value" with v3.99.9000

[marine-ecologist]

Example using the stars raster:

L7file = system.file("tif/L7_ETMs.tif", package = "stars")
L7 = read_stars(L7file)

### working but gives warning
tm_shape(L7) + 
   tm_raster(3, 2, 1)

# Warning message:
# In value[[3L]](cond) : could not rename the data.table

### not working gives error
tm_shape(L7) + 
   tm_rgb(3, 2, 1)

# Error: palette should be a character value
# In addition: Warning message:
# In value[[3L]](cond) : could not rename the data.table

[mtennekes]

Thx. It's already some time ago that I've worked on stars objects with bands and attributes. So I have to recall which function calls should be supported and that the 'correct' approach is.

At least, tmap4 does the 'multivariate' stuff via tm_mv and tm_mv_dim.

Since L7 is a stars object with a dimension called band this is the correct (but tedious looking) code:

tm_shape(L7) + 
	tm_raster(col = tm_mv_dim("band", c(3, 2, 1)), col.scale = tm_scale_rgb())

Or, shorter:

tm_shape(L7) + 
	tm_rgb(tm_mv_dim("band", c(3, 2, 1)))

Have to make sure your code works as well (backwards compatibility) or at least throws some useful errors.

Do you know if this code worked in earlier tmap4 development versions?

[mtennekes]

FYI: This works as well

L7split = split(L7)
tm_shape(L7split) + 
	tm_rgb(tm_mv("X3", "X2", "X1"))

but tm_rgb() does not because the default is tm_mv(3, 2, 1). So I need to make sure numbers are translated to attribute indices...