tm_lines and tm_text aimed to draw isopleths, which can be created with smooth_map.tm_iso(col = NA, text = "level", size = 0.5, remove.overlap = TRUE,
along.lines = TRUE, overwrite.lines = TRUE, ...)tm_lines."level" of the shape that is created with smooth_maptm_text)tm_texttm_texttm_textsmooth_map