grid_data: Function to grid geolocated observations on a map
In MarineEcosystemResearchProgramme/merpData: Mapping and enriching of marine data

Description Usage Arguments Value Examples

Data portals such as OBIS typically return tables of geolocated observations upon requests. Gridded data is often used to represent in a synthetic way this type of observations, but although R packages ggplot2 and ggmap are good at representing it, there is no built-in function to go from raw to aggregated data.

1 2	grid_data(lat, lon, myresolution = 0.5, myzoom = 7, lat_centre = NULL, lon_centre = NULL, map = FALSE)

`lat`	is a numerical vector of latitudes for the set of observations.
`lon`	is a numerical vector of longitudes for the set of observations.
`myresolution`	is the size of the cells the data is to be aggregated over
`myzoom`	is the zoom to be applied to plot the gridded data on ggmap map
`lat_centre`	is the user-defined latitude the map will be centred on. Default to mean latitude of observations.
`lon_centre`	is the user-defined longitude the map will be centred on. Default to mean longitude of observations.
`map`	controls whether a map should be computed while running `grid_data`. It is set by default to FALSE.

grid_data returns a data frame containing the number of observations per cell.

library(robis)
library(ggmap)
obs <- occurrence("Gadus morhua", year = 2002)
justchecking <- grid_data(lat = obs$decimalLatitude, lon = obs$decimalLongitude, myresolution = 0.5, myzoom = 4, map = TRUE)
# examine the data
head(justchecking$gridded_data)
# plot the data
justchecking$myplot