getCovariate: Extract Covariate Data from A list of Rasters

In surveyPrev: Mapping the Prevalence of Binary Indicators using Survey Data in Small Areas

Extract Covariate Data from A list of Rasters

Description

This function aligns raster covariates to a population density grid, extracts values for a national grid, associates administrative information, and prepares covariates for cluster-based data.

Usage

getCovariate(
  tiffs,
  tiff.population,
  UR.surface = NULL,
  cluster.info,
  poly.adm,
  by.adm,
  by.adm.upper,
  standardize = FALSE,
  na.rm = FALSE,
  fact = 1
)

Arguments

tiffs	A list of 'SpatRaster' with element names the column names for the covariates.
tiff.population	A 'SpatRaster' object representing population density used as the reference grid.
UR.surface	(Optional) A 'SpatRaster' object indicating urban-rural classification.
cluster.info	**Need STRATA here**
poly.adm	A 'sf' object
by.adm	the column name of column for Admin names for admin 1
by.adm.upper	the column name of column for Admin names for admin 2 or other lower admin level.
standardize	whether to standardize the covariates/tiffs or not
na.rm	whether to remove rows that have no Population or admin 2 membership
fact	A numeric value indicating the aggregation factor for resampling the raster data. If 'fact = 1', no aggregation is performed.

Details

The function follows these steps: 1. Converts 'poly.adm' to an 'sf' object. 2. Aligns rasters in 'tiffs' to match the 'tiff.population' grid using bilinear resampling. 3. Aggregates raster resolution if 'fact' is greater than 1. 4. Extracts pixel center coordinates and values for the national grid. 5. Matches pixel locations to administrative boundaries. 6. Extracts raster values at cluster locations.

Value

A list with two elements:

natl.grid	A data frame containing natl grid of pixels for covariates and Admin information.
cluster.cov	A data frame with extracted covariates for cluster locations. U/R info from DHS

Examples

## Not run: 

kenya_cov <- getCovariate(
    tiffs = cov_raster_stack,
    tiff.population = avg.pop,
    UR.surface = UR_surface,
    cluster.info = cluster.info,
    poly.adm = poly.adm2,
    by.adm = 'NAME_2',
    by.adm.upper = 'NAME_1',
    standardize=FALSE,
.    na.rm=FALSE,
    fact = 1)


## End(Not run)

surveyPrev documentation built on June 19, 2026, 5:06 p.m.