#load packages
#instal the packages before using install.packages("name of packages")
library(reshape2)
library(data.table)#to use the melt
library(ggplot2)#to plot, map_data, scale_fill_gradientn, etc
library(utils)#to read the data

#data directory
setwd("E:/My Drive/Mirror/data/")
elev_grid=read.delim("Elevation_grid_1deg.txt", header = TRUE, sep = "\t", dec = ".")
# prec=read.delim("Precipitaton_data.txt", header = TRUE, sep = "\t", dec = ".")

r_pal=terrain.colors(10)
xlim1=c(-115,-101.3)
ylim1=c(29.5,42.5)
df <- melt(elev_grid$Elev, na.rm = TRUE)

df$Lon <- elev_grid$Lon
df$Lat <- elev_grid$Lat 
names(df) <- c("elev","Lon", "Lat")
zlime=range(elev_grid$Elev)
# zlime[1]=0
zlab=seq(0,3500, by=500)
siz1=14
siz2=10
MainStates <- map_data("state")
states_full=c("arizona","colorado","new mexico","utah")

name="Elevation"
g1=ggplot() +
  geom_tile(data = df, aes(x = Lon, y = Lat, fill=elev))+
  geom_polygon( data=MainStates, aes(x=long, y=lat, group=group), color="gray20", fill="transparent" )+
  ggtitle("") +
  xlab("Longitude") +
  ylab("Latitude")+
  scale_fill_gradientn(name="Elevation (m)", colours = r_pal,limits=zlime,breaks=zlab,labels=zlab,guide="colourbar")+
  theme_bw()+
  theme(legend.position="right")+
  theme(panel.grid.major = element_line(colour = "grey50", linetype = "dashed"),
        legend.text = element_text(size = 10),plot.margin=unit(c(0.0,0.01,0.01,0.01),"in"))+
  coord_sf(xlim = xlim1, ylim = ylim1,label_axes = list(bottom = "E", left = "N"), expand =FALSE)

dev.new();g1
ggsave("Elevation.jpeg", width = 6, height = 5, units = 'in', bg = 'transparent') # save figure
dev.off