In r-tmap/tmap: Thematic Maps

knitr::opts_chunk$set(
  collapse = TRUE,
  out.width = "100%",
  dpi = 300,
  fig.width = 7.2916667,
  comment = "#>"
)
hook_output <- knitr::knit_hooks$get("output")
knitr::knit_hooks$set(output = function(x, options) {
   lines <- options$output.lines
   if (is.null(lines)) {
     return(hook_output(x, options))  # pass to default hook
   }
   x <- unlist(strsplit(x, "\n"))
   more <- "..."
   if (length(lines)==1) {        # first n lines
     if (length(x) > lines) {
       # truncate the output, but add ....
       x <- c(head(x, lines), more)
     }
   } else {
     x <- c(more, x[lines], more)
   }
   # paste these lines together
   x <- paste(c(x, ""), collapse = "\n")
   hook_output(x, options)
 })

library(tmap)
library(dplyr)
library(sf)
library(stars)
library(terra)
library(sits)
tmap_options(scale = 0.75)

About the data

ndvi_image = system.file("extdata/raster/mod13q1/TERRA_MODIS_012010_NDVI_2014-01-17.jp2", package = "sits")

Reading with the terra package

(ndvi_terra = terra::rast(ndvi_image))

Reading with the stars package

(ndvi_stars = stars::read_stars(ndvi_image))

Example 1

first plot - a NDVI image in false color with a brewer pallete

ndvi = ndvi_terra # or ndivi_stars

# scale the data to get image in [-1..1] range
ndvi = ndvi * 0.0001

# plot using brewer "RdYlGn" pallete
tmap::tm_shape(ndvi) +
    tmap::tm_raster(
        col.scale = tmap::tm_scale_continuous(
            values = "brewer.rd_yl_gn",
            midpoint = NA),
        col.legend = tmap::tm_legend(
            title = "NDVI",
            title.size = 0.7,
            text.size = 0.7,
            bg.color = "white",
            bg.alpha = 0.7,
            position = tmap::tm_pos_in("left", "bottom"),
            frame = TRUE
        )
    ) +
    tmap::tm_graticules(
        labels.size = 0.7
    ) +
    tmap::tm_compass() +
    tmap::tm_layout(
        scale = 1.0
    )

Example 2

sent_image = system.file("extdata/raster/classif/SENTINEL2_MSI_20LNR_2020-06-04_2021-08-26_class_v1.tif", package = "sits")

sent = terra::rast(sent_image)

tm_shape(sent) + tm_raster(col.scale = tm_scale_discrete())

Example 3 (categorical raster)

clc2018_poznan = rast("https://github.com/Nowosad/comparing-spatial-patterns-2024/raw/refs/heads/main/data/clc2018_poznan.tif")

tm_shape(clc2018_poznan) + 
    tm_raster()

tm_shape(clc2018_poznan) + 
    tm_raster(col.legend = tm_legend(title = "Land cover"))

r-tmap/tmap documentation built on Feb. 28, 2025, 7:54 a.m.