• Installation • Hello World • How does rgee work? • Guides • Contributing • Citation • Credits
Google Earth Engine is a cloud-based platform that enables users to access a petabyte-scale archive of remote sensing data and conduct geospatial analysis on Google's infrastructure. Currently, Google offers support only for Python and JavaScript. rgee
fills that gap by providing support for R!. Below, you will find a comparison between the syntax of rgee
and the two other client libraries supported by Google.
JS (Code Editor) | Python | R |
---|---|---|
``` javascript var db = 'CGIAR/SRTM90_V4' var image = ee.Image(db) print(image.bandNames()) #> 'elevation' ``` | ``` python import ee ee.Initialize() db = 'CGIAR/SRTM90_V4' image = ee.Image(db) image.bandNames().getInfo() #> [u'elevation'] ``` | ``` r library(rgee) ee_Initialize() db <- 'CGIAR/SRTM90_V4' image <- ee$Image(db) image$bandNames()$getInfo() #> [1] "elevation" ``` |
Quite similar, isn't it?. However, additional more minor changes should be considered when using Google Earth Engine with R. Please check the consideration section before you start coding!
NOTE: Create a .Renviron file file to prevent setting RETICULATE_PYTHON and EARTHENGINE_GCLOUD every time you authenticate/init your account.
library(rgee)
# Set your Python ENV
Sys.setenv("RETICULATE_PYTHON" = "/usr/bin/python3")
# Set Google Cloud SDK. Only need it the first time you log in.
Sys.setenv("EARTHENGINE_GCLOUD" = "home/csaybar/google-cloud-sdk/bin/")
ee_Authenticate()
# Init your Earth Session
ee_Initialize()
Install from CRAN with:
install.packages("rgee")
Install the development versions from github with
library(remotes)
install_github("r-spatial/rgee")
Furthermore, rgee
depends on numpy and earthengine-api and it requires gcloud CLI to authenticate new users. The following example shows how to install and set up 'rgee' on a new Ubuntu computer. If you intend to use rgee on a server, please refer to this example in RStudio Cloud." -- https://posit.cloud/content/5175749)
install.packages(c("remotes", "googledrive"))
remotes::install_github("r-spatial/rgee")
library(rgee)
# Get the username
HOME <- Sys.getenv("HOME")
# 1. Install miniconda
reticulate::install_miniconda()
# 2. Install Google Cloud SDK
system("curl -sSL https://sdk.cloud.google.com | bash")
# 3 Set global parameters
Sys.setenv("RETICULATE_PYTHON" = sprintf("%s/.local/share/r-miniconda/bin/python3", HOME))
Sys.setenv("EARTHENGINE_GCLOUD" = sprintf("%s/google-cloud-sdk/bin/", HOME))
# 4 Install rgee Python dependencies
ee_install()
# 5. Authenticate and init your EE session
ee_Initialize()
There are three (3) different ways to install rgee Python dependencies:
rgee::ee_install()
rgee::ee_install_set_pyenv(
py_path = "/home/csaybar/.virtualenvs/rgee/bin/python", # Change it for your own Python PATH
py_env = "rgee" # Change it for your own Python ENV
)
Take into account that the Python PATH you set must have earthengine-api and numpy installed. The use of miniconda/anaconda is mandatory for Windows users, Linux and MacOS users could also use virtualenv. See reticulate documentation for more details.
If you are using MacOS or Linux, you can choose setting the Python PATH directly:
rgee::ee_install_set_pyenv(
py_path = "/usr/bin/python3",
py_env = NULL
)
However, rgee::ee_install_upgrade and reticulate::py_install will not work until you have set up a Python ENV.
After install Python dependencies
, you might want to use the function below for checking the rgee status.
ee_check() # Check non-R dependencies
library(reticulate)
library(rgee)
# 1. Initialize the Python Environment
ee_Initialize()
# 2. Install geemap in the same Python ENV that use rgee
py_install("geemap")
gm <- import("geemap")
Upgrade the earthengine-api
library(rgee)
ee_Initialize()
ee_install_upgrade()
rgee
functions have the prefix ee_. Auto-completion is your best ally :).rgee
is "pipe-friendly"; we re-export %>% but do not require to use it.Authenticate and Initialize the Earth Engine R API.
library(rgee)
ee_Initialize()
Let's create a new band containing the image date as years since 1991 by extracting the year of the image acquisition date and subtracting it from 1991.
createTimeBand <-function(img) {
year <- ee$Date(img$get('system:time_start'))$get('year')$subtract(1991L)
ee$Image(year)$byte()$addBands(img)
}
Use your TimeBand function to map it over the night-time lights collection.
collection <- ee$
ImageCollection('NOAA/DMSP-OLS/NIGHTTIME_LIGHTS')$
select('stable_lights')$
map(createTimeBand)
Compute a linear fit over the series of values at each pixel, so that you can visualize the y-intercept as green, and the positive/negative slopes as red/blue.
col_reduce <- collection$reduce(ee$Reducer$linearFit())
col_reduce <- col_reduce$addBands(
col_reduce$select('scale'))
ee_print(col_reduce)
Let's visualize our map!
Map$setCenter(9.08203, 47.39835, 3)
Map$addLayer(
eeObject = col_reduce,
visParams = list(
bands = c("scale", "offset", "scale"),
min = 0,
max = c(0.18, 20, -0.18)
),
name = "stable lights trend"
)
Install and load tidyverse
and sf
R packages, and initialize the Earth Engine R API.
library(tidyverse)
library(rgee)
library(sf)
ee_Initialize()
Read the nc
shapefile.
nc <- st_read(system.file("shape/nc.shp", package = "sf"), quiet = TRUE)
We will use the Terraclimate dataset to extract the monthly precipitation (Pr) from 2001
terraclimate <- ee$ImageCollection("IDAHO_EPSCOR/TERRACLIMATE") %>%
ee$ImageCollection$filterDate("2001-01-01", "2002-01-01") %>%
ee$ImageCollection$map(function(x) x$select("pr")) %>% # Select only precipitation bands
ee$ImageCollection$toBands() %>% # from imagecollection to image
ee$Image$rename(sprintf("PP_%02d",1:12)) # rename the bands of an image
ee_extract
will help you to extract monthly precipitation values from the Terraclimate ImageCollection. ee_extract
works similar to raster::extract
, you just need to define: the ImageCollection object (x), the geometry (y), and a function to summarize the values (fun).
ee_nc_rain <- ee_extract(x = terraclimate, y = nc["NAME"], sf = FALSE)
Use ggplot2 to generate a beautiful static plot!
ee_nc_rain %>%
pivot_longer(-NAME, names_to = "month", values_to = "pr") %>%
mutate(month, month=gsub("PP_", "", month)) %>%
ggplot(aes(x = month, y = pr, group = NAME, color = pr)) +
geom_line(alpha = 0.4) +
xlab("Month") +
ylab("Precipitation (mm)") +
theme_minimal()
Install and load sf
. after that, initialize the Earth Engine R API.
library(magick)
library(rgee)
library(sf)
ee_Initialize()
Define the regional bounds of animation frames and a mask to clip the NDVI data by.
mask <- system.file("shp/arequipa.shp", package = "rgee") %>%
st_read(quiet = TRUE) %>%
sf_as_ee()
region <- mask$geometry()$bounds()
Retrieve the MODIS Terra Vegetation Indices 16-Day Global 1km dataset as an ee.ImageCollection
and then, select the NDVI band.
col <- ee$ImageCollection('MODIS/006/MOD13A2')$select('NDVI')
Group images by composite date
col <- col$map(function(img) {
doy <- ee$Date(img$get('system:time_start'))$getRelative('day', 'year')
img$set('doy', doy)
})
distinctDOY <- col$filterDate('2013-01-01', '2014-01-01')
Now, let's define a filter that identifies which images from the complete collection match the DOY from the distinct DOY collection.
filter <- ee$Filter$equals(leftField = 'doy', rightField = 'doy')
Define a join and convert the resulting FeatureCollection to an ImageCollection... it will take you only 2 lines of code!
join <- ee$Join$saveAll('doy_matches')
joinCol <- ee$ImageCollection(join$apply(distinctDOY, col, filter))
Apply median reduction among the matching DOY collections.
comp <- joinCol$map(function(img) {
doyCol = ee$ImageCollection$fromImages(
img$get('doy_matches')
)
doyCol$reduce(ee$Reducer$median())
})
Almost ready! but let's define RGB visualization parameters first.
visParams = list(
min = 0.0,
max = 9000.0,
bands = "NDVI_median",
palette = c(
'FFFFFF', 'CE7E45', 'DF923D', 'F1B555', 'FCD163', '99B718', '74A901',
'66A000', '529400', '3E8601', '207401', '056201', '004C00', '023B01',
'012E01', '011D01', '011301'
)
)
Create RGB visualization images for use as animation frames.
rgbVis <- comp$map(function(img) {
do.call(img$visualize, visParams) %>%
ee$Image$clip(mask)
})
Let's animate this. Define GIF visualization parameters.
gifParams <- list(
region = region,
dimensions = 600,
crs = 'EPSG:3857',
framesPerSecond = 10
)
Get month names
dates_modis_mabbr <- distinctDOY %>%
ee_get_date_ic %>% # Get Image Collection dates
'[['("time_start") %>% # Select time_start column
lubridate::month() %>% # Get the month component of the datetime
'['(month.abb, .) # subset around month abbreviations
And finally, use ee_utilsgif\* functions to render the GIF animation and add some texts.
animation <- ee_utils_gif_creator(rgbVis, gifParams, mode = "wb")
animation %>%
ee_utils_gif_annotate(
text = "NDVI: MODIS/006/MOD13A2",
size = 15, color = "white",
location = "+10+10"
) %>%
ee_utils_gif_annotate(
text = dates_modis_mabbr,
size = 30,
location = "+290+350",
color = "white",
font = "arial",
boxcolor = "#000000"
) # -> animation_wtxt
# ee_utils_gif_save(animation_wtxt, path = "raster_as_ee.gif")
rgee
is not a native Earth Engine API like the Javascript or Python client. Developing an Earth Engine API from scratch would create too much maintenance burden, especially considering that the API is in active development. So, how is it possible to run Earth Engine using R? the answer is [reticulate]! (https://rstudio.github.io/reticulate/). reticulate
is an R package designed to allow seamless interoperability between R and Python. When an Earth Engine request is created in R, reticulate
will translate this request into Python and pass it to the Earth Engine Python API
, which converts the request to a JSON
format. Finally, the request is received by the GEE Platform through a Web REST API. The response will follow the same path in reverse.
Please note that the rgee
project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.
👍 Thanks for taking the time to contribute! 🎉👍 Please review our Contributing Guide.
Enjoying rgee? Let others know about it! Share it on Twitter, LinkedIN or in a blog post to spread the word.
Using rgee for your scientific article? here's how you can cite it
citation("rgee")
To cite rgee in publications use:
C Aybar, Q Wu, L Bautista, R Yali and A Barja (2020) rgee: An R
package for interacting with Google Earth Engine Journal of Open
Source Software URL https://github.com/r-spatial/rgee/.
A BibTeX entry for LaTeX users is
@Article{,
title = {rgee: An R package for interacting with Google Earth Engine},
author = {Cesar Aybar and Quisheng Wu and Lesly Bautista and Roy Yali and Antony Barja},
journal = {Journal of Open Source Software},
year = {2020},
}
We want to offer a special thanks :raised_hands: :clap: to Justin Braaten for his wise and helpful comments in the whole development of rgee. As well, we would like to mention the following third-party R/Python packages for contributing indirectly to the improvement of rgee: