Map plot for H-1B Shiny

map.R

require(ggmap)
require(ggrepel)
require(dplyr)
require(ggplot2)

USA = map_data(map = "usa")

# Layer 1: USA Map
ggplot(USA, aes(x=long, y=lat)) + 
geom_polygon() + xlab("Longitude (deg)") + ylab("Latitude(deg)") + 

# Layer 2: Point plot with bubble size directly proportional to metric and
# bubble transparency inversely proportional to metric
geom_point(data=map_df, aes_string(x="lon", y="lat", label = "WORKSITE", alpha = metric, size = metric), color="yellow") + 

# Layer 3: Pointer to Top locations. Number of Top selected by Plot Categories Input of the App
geom_label_repel(data=map_df %>% filter(WORKSITE %in% top_locations),aes_string(x="lon", y="lat",label = "WORKSITE"),
                     fontface = 'bold', color = 'black',
                     box.padding = unit(0.0, "lines"),
                     point.padding = unit(1.0, "lines"),
                     segment.color = 'grey50',
                     force = 3) + 
# USA Boundaries                     
coord_map(ylim = c(23,50),xlim=c(-130,-65))