day18.rmd

---
title: "day18"
author: "Xingxin Li"
date: "9/2/2020"
output: html_document
---

```{r, message = FALSE, warning = FALSE}
library(elevatr)
library(tidyverse)
library(ggplot2)
library(sf)
library(raster)
```


```{r, message = FALSE, warning = FALSE}

r = raster("/Users/xingxin/Github/geog176a-summer-2020-lab1/goletaelev.tif")

threshold = function(x) {ifelse(x <= 0 , NA, 1)}

threshold(-100)

(m = calc(r, threshold))

plot(r)

plot(m, col = "black")

ocean_cut = m * r

plot(ocean_cut, col = viridis::viridis(256))

(rcl = data.frame(min = seq(0,500,100),max =  seq(100,600, 100), lab = c(0:5)))

(rc = reclassify(ocean_cut, rcl, lowerTRUE = TRUE))

(s = stack(r, m, ocean_cut, rc) %>% 
  setNames(c("elevation", "land-mask", "terrain", "topography")))

plot(s, col = viridis::viridis(256))

```