View source: R/lognorm_profile.R
lognorm_profile | R Documentation |
An implementation of the lognormal decay model for serial crime analysis within 'CrimeStat'. This model is very similar to the normal model except with more skew to either side. If there is reason to believe that the perpetrator's residence is closer to the incidents, this function can take the form of a very rapid increase near incident with a gradual decline from the peak likelihood.
lognorm_profile(lat, lon, a = NULL, d_mean = NULL, sd = NULL, n = NULL)
lat |
a vector of latitudes for the crime incident series |
lon |
a vector of latitudes for the crime incident series |
a |
coefficient for the normal decay function. If |
d_mean |
mean distance. If |
sd |
standard deviation of the distances. If |
n |
total number of cells within the spatial grid for the jeopardy surface.
If |
A data frame of points depicting a spatial grid of the hunting area for the given incident locations. Also given are the resultant summed values (score) for each map point. A higher resultant score indicates a greater the probability that point contains the offender's anchor point.
Jamie Spaulding, Keith Morris
Ned Levine, CrimeStat IV: A Spatial Statistics Program for the Analysis of Crime Incident Locations (version 4.0). Ned Levine & Associates, Houston, TX, and the National Institute of Justice, Washington, DC, June 2013.
#Using provided dataset for the Boston Strangler Incidents: data(desalvo) test <- lognorm_profile(desalvo$lat, desalvo$lon) g_map = sp::SpatialPixelsDataFrame(points = test[c("lons", "lats")], data = test) g_map <- raster::raster(g_map) # Assign a Coordinate Reference System for the Raster raster::crs(g_map) <- sp::CRS("+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs") # Define a Parula Color Pallete for Resultant Jeopardy Surface library(leaflet) #for mapping the geographic profile pal <- colorNumeric(pals::parula(200), raster::values(g_map), na.color = "transparent") leaflet() %>% addTiles() %>% addProviderTiles('Esri.WorldTopoMap', group = 'Topo') %>% addAwesomeMarkers(lng = -71.07357, lat = 42.41322, icon = awesomeIcons(icon = 'home', markerColor = 'green'), popup = 'Residence') %>% addRasterImage(g_map, colors = pal, opacity = 0.6) %>% addLegend(pal = pal, values = raster::values(g_map), title = 'Score') %>% addCircleMarkers(lng = desalvo$lon, lat = desalvo$lat, radius = 4, opacity = 1, fill = 'black', stroke = TRUE, fillOpacity = 0.75, weight = 2, fillColor = "red")
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