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,
  quiet = FALSE,
  ...
)

Arguments

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?

quiet

Logical. Suppress info message.

...

ee$Image$reduceRegions additional parameters. See ee_help(ee$Image$reduceRegions) for more details.

Value

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).

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.

Examples

if (FALSE) { library(rgee) library(sf) ee_Initialize() # 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 ee_nc_rain <- ee_extract( x = terraclimate, y = nc["NAME"], scale = 250, fun = ee$Reducer$mean(), sf = TRUE ) # Spatial plot plot( ee_nc_rain["X200101_Terraclimate_pp_2001_01_01"], main = "2001 Jan Precipitation - Terraclimate", reset = FALSE ) }