ee_extract: Extract values from EE Images or ImageCollections objects
In csaybar/rgee: R Bindings for Calling the 'Earth Engine' API

Description Usage Arguments Details Value Examples

Extract values from a ee$Image at the locations of a geometry object. You can use ee$Geometry$*, ee$Feature, ee$FeatureCollection, sf or sfc objects. This function mimicking how extract currently works.

ee_extract(
  x,
  y,
  fun = ee$Reducer$mean(),
  scale = NULL,
  sf = FALSE,
  via = "getInfo",
  container = "rgee_backup",
  lazy = FALSE,
  quiet = FALSE,
  ...
)

`x`	ee$Image.
`y`	ee$Geometry$*, ee$Feature, ee$FeatureCollection, sfc or sf objects.
`fun`	ee$Reducer object. Function to summarize the values. The function must take a single numeric value as an argument and return a single value. See details.
`scale`	A nominal scale in meters of the Image projection to work in. By default 1000.
`sf`	Logical. Should return a sf object?
`via`	Character. Method to export the image. Three method are implemented: "getInfo", "drive", "gcs".
`container`	Character. Name of the folder ('drive') or bucket ('gcs') to be exported into (ignore if `via` is not defined as "drive" or "gcs").
`lazy`	Logical. If TRUE, a `future::sequential` object is created to evaluate the task in the future. Ignore if `via` is set as "getInfo". See details.
`quiet`	Logical. Suppress info message.
`...`	ee$Image$reduceRegions additional parameters. See `ee_help(ee$Image$reduceRegions)` for more details.

The reducer functions that return one value are:

allNonZero: Returns a Reducer that returns 1 if all of its inputs are non-zero, 0 otherwise.
anyNonZero: Returns a Reducer that returns 1 if any of its inputs are non-zero, 0 otherwise.
bitwiseAnd: Returns a Reducer that computes the bitwise-and summation of its inputs.
bitwiseOr: Returns a Reducer that computes the bitwise-or summation of its inputs.
count: Returns a Reducer that computes the number of non-null inputs.
first: Returns a Reducer that returns the first of its inputs.
firstNonNull: Returns a Reducer that returns the first of its non-null inputs.
kurtosis: Returns a Reducer that Computes the kurtosis of its inputs.
last: Returns a Reducer that returns the last of its inputs.
lastNonNull: Returns a Reducer that returns the last of its non-null inputs.
max: Creates a reducer that outputs the maximum value of its (first) input. If numInputs is greater than one, also outputs the corresponding values of the additional inputs.
mean: Returns a Reducer that computes the (weighted) arithmetic mean of its inputs.
median: Create a reducer that will compute the median of the inputs. For small numbers of inputs (up to maxRaw) the median will be computed directly; for larger numbers of inputs the median will be derived from a histogram.
min: Creates a reducer that outputs the minimum value of its (first) input. If numInputs is greater than one, also outputs additional inputs.
mode: Create a reducer that will compute the mode of the inputs. For small numbers of inputs (up to maxRaw) the mode will be computed directly; for larger numbers of inputs the mode will be derived from a histogram.
product: Returns a Reducer that computes the product of its inputs.
sampleStdDev: Returns a Reducer that computes the sample standard deviation of its inputs.
sampleVariance: Returns a Reducer that computes the sample variance of its inputs.
stdDev: Returns a Reducer that computes the standard deviation of its inputs.
sum: Returns a Reducer that computes the (weighted) sum of its inputs.
variance: Returns a Reducer that computes the variance of its inputs.

A data.frame or an sf object depending on the sf argument. Column names are extracted from band names, use ee$Image$rename to rename the bands of an ee$Image. See ee_help(ee$Image$rename).

## Not run: 
library(rgee)
library(sf)

ee_Initialize(gcs = TRUE, drive = TRUE)

# Define a Image or ImageCollection: Terraclimate
terraclimate <- ee$ImageCollection("IDAHO_EPSCOR/TERRACLIMATE") %>%
 ee$ImageCollection$filterDate("2001-01-01", "2002-01-01") %>%
ee$ImageCollection$map(
   function(x) {
     date <- ee$Date(x$get("system:time_start"))$format('YYYY_MM_dd')
     name <- ee$String$cat("Terraclimate_pp_", date)
     x$select("pr")$rename(name)
   }
 )

# Define a geometry
nc <- st_read(
 dsn = system.file("shape/nc.shp", package = "sf"),
 stringsAsFactors = FALSE,
 quiet = TRUE
)


#Extract values - getInfo
ee_nc_rain <- ee_extract(
 x = terraclimate,
 y = nc["NAME"],
 scale = 250,
 fun = ee$Reducer$mean(),
 sf = TRUE
)

# Extract values - drive (lazy = TRUE)
ee_nc_rain <- ee_extract(
 x = terraclimate,
 y = nc["NAME"],
 scale = 250,
 fun = ee$Reducer$mean(),
 via = "drive",
 lazy = TRUE,
 sf = TRUE
)
ee_nc_rain <- ee_nc_rain %>% ee_utils_future_value()

# Extract values - gcs (lazy = FALSE)
ee_nc_rain <- ee_extract(
 x = terraclimate,
 y = nc["NAME"],
 scale = 250,
 fun = ee$Reducer$mean(),
 via = "gcs",
 container = "rgee_dev",
 sf = TRUE
)

# Spatial plot
plot(
 ee_nc_rain["X200101_Terraclimate_pp_2001_01_01"],
 main = "2001 Jan Precipitation - Terraclimate",
 reset = FALSE
)

## End(Not run)