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I have a data frame of lat lons that surround a center point. The lat lons represent two groups. The groups are represented with a 1 or a 0. I can plot around the center point with different shapes and colors, but then I would like the colors to be more distinct. I would also like to plot two circles around the points, 300 meters, and 600 meters respectively. I have tried working with

Plot circle with a certain radius around point on a map in ggplot2

but have had no luck

a small sample looks like this

lat <- c(42.99052, 42.99085, 42.99046, 42.99081, 42.99197, 42.99122, 42.99154,42.99161, 42.99102, 42.99014, 42.98966, 42.99091, 42.99092, 42.99114 ,42.99000)
lon <-c(78.69961, -78.69871, -78.69878, -78.69868, -78.69825, -78.69929, -78.69784, -78.69960, -78.69904, -78.69918, -78.69998, -78.69746, -78.70145, -78.70020, -78.70010)
response <- c(0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1)
data <- data.frame(lat, lon, response)

My center point is 

(42.990707, -78.698899)

I get my map without circles and distinct colors like this

library(ggplot2)
library(ggmap)
library(viridis)

#getting map

mapgilbert <- get_map(location = c(lon = -78.698899 , lat=42.990707), zoom = 17,
                  maptype = "terrain", scale = 2)

ggmap(mapgilbert) +
  geom_point(data = data, aes(x = lon, y = lat, color = response , alpha = 1, fill = response),
           size = 2, shape = response) +
  guides(fill = FALSE, alpha = FALSE, size = FALSE) +
  scale_color_viridis(begin = 0, end = .7)

any help would be appreciated.

Nate
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mikeL
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  • I recommend that you follow this answer from the question you linked to: https://stackoverflow.com/a/34187878/7446435 You may need to learn a little about projections but it's basically the most simple way to accurately get what you need. – Jul Oct 21 '17 at 00:29
  • @ Mikel Arnaiz , why are you plotting circles for? ;-) – Tony_KiloPapaMikeGolf Nov 02 '17 at 12:01

1 Answers1

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I got the solution by modifying the answer in

Plot circle with a certain radius around point on a map in ggplot2

center_df<-data.frame(ID=c(1),lon=c(-78.698899),lat=c(42.990707))

make_circles <- function(centers, radius, nPoints = 500){
    # centers: the data frame of centers with ID
    # radius: radius measured in kilometer
    #
    meanLat <- mean(centers$lat)
    # length per longitude changes with lattitude, so need correction
    radiusLon <- radius /111 / cos(meanLat/57.3) 
    radiusLat <- radius / 111
    circleDF <- data.frame(ID = rep(centers$ID, each = nPoints))
    angle <- seq(0,2*pi,length.out = nPoints)

    circleDF$lon <- unlist(lapply(centers$lon, function(x) x + radiusLon * cos(angle)))
    circleDF$lat <- unlist(lapply(centers$lat, function(x) x + radiusLat * sin(angle)))
    return(circleDF)
}



myCircles <- make_circles(center_df, 0.2)
myCircles2 <- make_circles(center_df, 0.1)
mapgilbert2<- get_map(location = c(lon = -78.70000 , lat=42.991107), zoom = 16,
                  maptype = "terrain", scale = 2)

ggmap(mapgilbert2)+
geom_point(data = data, aes(x = lon, y = lat, fill=as.factor(exposure) , alpha = 1), size = 2, pch=21)+
guides(fill=FALSE, alpha=FALSE, size=guide_legend)+ 
scale_color_viridis(begin = 0, end = .7)+
geom_point(data=myCircles,aes(x=lon,y=lat), color='red')+
geom_point(data=myCircles2,aes(x=lon,y=lat), color='blue')+
scale_fill_manual(values=c("purple",  "green"))
mikeL
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