R/eq_map.R

In RussellPolitzky/quake: Earthquake Data Visualizations

#' @title Show Earthquakes on a map with annotations
#'
#' @description \code{eq_map} takes a \code{data.frame} with NOAA
#' earthquake data, and plots those on an interactive map, along with
#' annotations.  In addition to NOAA data, \code{eq_map} also takes a
#' parameter indicating which \code{data.frame} column to use for
#' marker, pop-up annotations.
#'
#' \code{eq_map} expects to find epicenter lattiude, longitude and earthquake
#' magnitude in the \code{LATTITUDE}, \code{LONGITUDE} and \code{EQ_PRIMARY}
#' columns respectively.
#'
#' @param data is a \code{data.frame} containing earthquake data
#' filtered to show quakes in an area of interest.
#' @param annot_col is a \code{string} which is the \code{data.frame}
#' column name carrying annotations for marker pop-ups.  The annotation
#' may be plain text or HTML.
#'
#' @return \code{eq_map} returns a \code{leaflet} map object,
#'
#' @importFrom magrittr "%>%"
#' @importFrom leaflet leaflet
#' @importFrom leaflet addTiles
#' @importFrom leaflet addCircleMarkers
#' @importFrom stats as.formula
#'
#' @example inst/examples/example_mapping_functions.R
#'
#' @seealso \link{leaflet}
#'
#' @export
eq_map <- function(data, annot_col) {
  leaflet::leaflet() %>%
    leaflet::addTiles() %>%
    leaflet::addCircleMarkers(
      data   = data,
      lng    = ~ LONGITUDE,
      lat    = ~ LATITUDE,
      weight = 1,
      radius = ~ EQ_PRIMARY,
      popup  = stats::as.formula(paste( "~", annot_col)) # Note ,as.formula allows dynamic formula creation.
    )
}