Create Contour Polygons from Regular Grids.

mapiso

The goal of mapiso is to ease the transformation of regularly spaced grids containing continuous data into contour polygons. These grids can be defined by data.frames (x, y, value), sf objects or SpatRasters from terra.
mapsio is a wrapper around isoband.

Installation

You can install the released version of mapiso from CRAN with:

install.packages("mapiso")

Alternatively, you can install the development version of mapiso from GitHub with:

remotes::install_github("riatelab/mapiso")

Usage

Raster

library(mapiso)
library(terra)
#> terra 1.7.29
library(mapsf)
r <- rast(system.file("tif/elevation.tif", package = "mapiso"))
isor <- mapiso(x = r)
mf_theme(mar = c(0, 0, 0, 0))
mf_raster(r)
mf_map(isor, col = NA, add = TRUE)

sf regular grid

library(mapiso)
library(sf)
#> Linking to GEOS 3.9.0, GDAL 3.2.2, PROJ 7.2.1; sf_use_s2() is TRUE
library(mapsf)
# gridded data
s <- st_read(system.file("gpkg/elevation.gpkg", package = "mapiso"), 
             layer = "elevation", quiet = TRUE)
# mask
m <- st_read(system.file("gpkg/elevation.gpkg", package = "mapiso"),
             layer = "com", quiet = TRUE)
# custom breaks
bks <-c(98,100, 150, 200, 250, 300, 350, 400, 412.6) 
isos <- mapiso(x = s, var = "elevation", breaks = bks, mask = m)
mf_map(isos, "isomin", "choro", 
       breaks = bks, border = NA, 
       leg_title = "elevation")
mf_map(m, col = NA, add = TRUE)
mf_map(s, cex = 1, pch = ".", col = "grey20", add = TRUE)

data.frame

library(mapiso)
library(mapsf)
d <- read.csv(system.file("csv/elevation.csv", package = "mapiso"))
head(d)
#>          x       y elevation
#> 1 586231.3 6431677  282.0299
#> 2 586481.3 6431677  263.7194
#> 3 586731.3 6431677  244.9597
#> 4 586981.3 6431677  222.3232
#> 5 587231.3 6431677  211.1522
#> 6 587481.3 6431677  232.1604
isod <- mapiso(x = d, var = 'elevation', coords = c('x', 'y'), crs = 'epsg:2154')
bks <- unique(c(isod$isomin, isod$isomax))
mf_map(isod, "isomin", "choro", breaks = bks, leg_title = "elevation")

Community Guidelines

One can contribute to the package through pull requests and report issues or ask questions here.
This project uses conventional commits and semantic versioning.