# Tue Dec 15 14:59:49 2020 -

# 字符编码：UTF-8
# R 版本：R x64 4.0.3 for window 10
# cgh163email@163.com
# 个人笔记不负责任
# —— 拎了个梨🍐
.rs.restartR()
require(terra)
# deratify转换为因素
rm(list=ls());gc()

set.seed(0)
r <- raster(nrow=10, ncol=10)
values(r) <- runif(ncell(r)) * 10
is.factor(r)

r <- round(r)
f <- as.factor(r)
is.factor(f)
# Tue Dec 15 15:04:03 2020 -- 已经转为了rs对象
x <- levels(f)[[1]]
x
x$code <- letters[10:20]
levels(f) <- x
levels(f)
f

r <- raster(nrow=10, ncol=10)
values(r) = 1
r[51:100] = 2
r[3:6, 1:5] = 3
r <- ratify(r)
plot(r)
rat <- levels(r)[[1]]
rat$landcover <- c('Pine', 'Oak', 'Meadow')
rat$code <- c(12,25,30)
levels(r) <- rat
r

# extract values for some cells
i <- extract(r, c(1,2, 25,100))
i
# get the attribute values for these cells
factorValues(r, i)

# write to file:
# rr <- writeRaster(r, rasterTmpFile(), overwrite=TRUE)
# rr

# create a single-layer factor
x <- deratify(r, 'landcover')
x
is.factor(x)
levels(x)