r - 将 colorFactor 调色板添加到 mapview 对象

Question

目的是为因子值提供固定颜色。我很难将 colorFactor 比例应用于 mapview 对象。但是，调色板似乎与 zcol 不匹配。

我尝试了以下，类似于传单 map 。

library(mapview)

colors <- colorFactor(palette = c("Red", "Green", "Blue"),
                      levels = c("Oberfranken","Mittelfranken", "Unterfranken"))

mapview(franconia, zcol = "district",col.regions=colors)

我收到以下错误消息:

1: In col.regions(nregions) :   Some values were outside the color
scale and will be treated as NA

有什么帮助吗？

以下内容适用于传单，但不使用 mapview。

franconia %>% leaflet() %>% addTiles() %>% addPolygons(fillColor = ~colors(district))

Answer 1

我不知道如何使用贝尼的回答来指定我想将哪种颜色应用于 map 上的特定要素。

原来 colorFactor 返回一个函数。您需要提供要用于为要素着色的字段:

library('sf')
library('leaflet')
library('mapview')
# Read in shapefile and keep the first three features
ncShp <- st_read(system.file("shape/nc.shp", package="sf"))[1:3, ]
ncShp
# Simple feature collection with 3 features and 14 fields
# Geometry type: MULTIPOLYGON
# Dimension:     XY
# Bounding box:  xmin: -81.74107 ymin: 36.23388 xmax: -80.43531 ymax: 36.58965
# Geodetic CRS:  NAD27
# AREA PERIMETER CNTY_ CNTY_ID      NAME  FIPS FIPSNO CRESS_ID BIR74 SID74 NWBIR74 BIR79 SID79 NWBIR79                       geometry
# 1 0.114     1.442  1825    1825      Ashe 37009  37009        5  1091     1      10  1364     0      19 MULTIPOLYGON (((-81.47276 3...
# 2 0.061     1.231  1827    1827 Alleghany 37005  37005        3   487     0      10   542     3      12 MULTIPOLYGON (((-81.23989 3...
# 3 0.143     1.630  1828    1828     Surry 37171  37171       86  3188     5     208  3616     6     260 MULTIPOLYGON (((-80.45634 3...

cols <- c('red', 'green', 'blue')

# Colour our features sequentially based on the NAME field
ncShp$NAME
# [1] "Ashe"      "Alleghany" "Surry" 
# Ashe will be red, Alleghany will be green, Surry will be blue

colPal <- leaflet::colorFactor(palette = cols, levels = ncShp$NAME)
# Note: use levels(ncShp$NAME) if it's already a factor

# Send it to mapview
mapview::mapview(ncShp, zcol='NAME', col.regions=colPal(ncShp$NAME))