create multiband raster using individual rasters in terra

Question

To put individual rasters into single raster as individual layers, I would do this:

library(raster)
    
rast1 <- terra::rast('rast1.tif')
rast2 <- terra::rast('rast2.tif')
rast3 <- terra::rast('rast3.tif')
    
single_raster <- c(rast1, rast2, rast3)
 

How can I do it programtically incase I have many more rasters in the working directory. I tried this:

raster_list <- list.files(pattern = ".tif") # get list of all rasters in my working directory 
temp_vec <- rep(NA, length(raster_list)) # create a empty vector with predefined length 
    
for(r in seq_along(raster_list)){ # run loop and put each raster in the empty vector
      
        raster_file <- raster_list[r]
        temp <- terra::rast(raster_file)
        temp_vec[r] <- temp
 }
    

The temp_vec is still NA and I get below warning.

    Warning messages:
      1: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length
    2: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length
    3: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length
    4: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length
    5: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length
    6: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length
    7: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length
    8: In raster_vec[r] <- temp :
      number of items to replace is not a multiple of replacement length        

The reason I am doing this so that I can create an animation using the multiband raster and save as a gif as follows:

terra::animate(temp_vec)

Answer 1

With terra, it is very simple:

terra::rast(raster_list)

So you do not need any loop.

A reproducible example:

library(terra)

paths = rep(system.file("ex/elev.tif", package="terra"), 10)

r = rast(paths)

set.seed(3) # for reproducibility

# multiply each layer by a random value (because they are the same in the example)
r = r * runif(10) # to make animation less boring

animate(r)