3 Map

Learning Objectives

• TBD

3.1 Read Spatial Data

Open your r3-exercises.Rproj to launch RStudio into that project and set the working directory.

Create a new Rmarkdown file (RStudio menu File > New file > Rmarkdown…) called map.Rmd. Insert headers like last time followed by Chunks of R code according to the examples provided below.

I’ll be copy/pasting during the demonstration but I encourage you to type out the text to enhance understanding.

3.1.1 Install packages

# require() is like library() except returns FALSE if missing (vs error)
if (!require(librarian)){
  install.packages("librarian")
  library(librarian)
}
# librarian::shelf() is like library() except installs package if missing, 
#   even from Github if include owner/repo
shelf(
  NOAA-EDAB/ecodata,
  sf)
# librarian before version 1.8.1, got error:
#   download from 'https://api.github.com/repos/NOAA-EDAB/ecodata/tarball/HEAD' failed

3.2 Get spatial data

ecodata::epu_sf

## Simple feature collection with 4 features and 3 fields
## Geometry type: MULTIPOLYGON
## Dimension:     XY
## Bounding box:  xmin: -77 ymin: 35.8327 xmax: -65.66667 ymax: 44.66667
## Geodetic CRS:  NAD83
##   EPU Shape_Leng Shape_Area                       geometry
## 0  GB   16.33086   6.162033 MULTIPOLYGON (((-66.5 42.16...
## 1 GOM   32.20684   7.545063 MULTIPOLYGON (((-69.26278 4...
## 2  SS   20.52712   3.350430 MULTIPOLYGON (((-67.54 44.6...
## 3 MAB   83.38407  15.695390 MULTIPOLYGON (((-75.97418 3...

epu_sf <- ecodata::epu_sf %>% 
  st_transform(4326)

So we see a geometry list column.

class(epu_sf)

## [1] "sf"         "data.frame"

# "sf"         "data.frame"
g1 <- epu_sf$geometry[1]
# see in Environment pane, expand g1

plot(epu_sf)

plot(epu_sf["EPU"])

Where in the world is this?

shelf(mapview)

mapview(epu_sf)