Zip_Choropleth地图制作：解决超时问题及优化需求

一、原始超时问题的根因与解决 #

运行zip_choropleth时卡顿超时，核心原因是输入数据包含非亚利桑那州的邮编，导致程序加载并处理大量无关地理数据。通过过滤仅保留亚利桑那州的邮编即可彻底解决该问题。

二、地图优化方案实现 #

针对当前需求，需完成两项优化，以下是整合后的完整可运行代码：

准备依赖与数据 #

# 安装并加载所需包
devtools::install_github("arilamstein/choroplethrZip@v1.5.0")
library(choroplethrZip)
library(dplyr)
library(choroplethr)
library(ggplot2)

# 已过滤为亚利桑那州邮编的目标数据
Pop_Zip <- structure(list(
  region = c("85324", "85332", "85360", "85362", "85901", "85902", "85911", "85912", "85920", "85923"), 
  value = c(363L, 238L, 75L, 71L, 4454L, 136L, 68L, 31L, 39L, 132L)), 
  class = c("grouped_df", "tbl_df", "tbl", "data.frame"), 
  row.names = c(NA, -10L), 
  groups = structure(list(region = c("85324", "85332", "85360", "85362", "85901", "85902", "85911", "85912", "85920", "85923"), 
                          .rows = structure(list(1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L), ptype = integer(0), class = c("vctrs_list_of", "vctrs_vctr", "list"))), 
                     class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA, -10L), .drop = TRUE))

整合两项优化的地图代码 #

# 定义需要叠加边界的亚利桑那县
AZ_County <- c("Apache County", "Coconino County", "Mohave County", 
               "Navajo County", "Yavapai County")

# 获取目标县的地理数据
county_data <- get_county_map(state = "arizona", resolution = 2) %>%
  filter(NAME %in% AZ_County)

# 绘制地图并应用优化
zip_choropleth(Pop_Zip, 
               state_zoom = "arizona",
               title      = "Test",
               legend     = "Population"
) + 
  # 应用指定的自定义渐变调色板
  scale_fill_gradientn(colours = c("#FFFFFF","#f688ee","#000775"), 
                       name = "Population") +
  # 叠加目标县的黑色边界线
  geom_polygon(data = county_data, aes(x = long, y = lat, group = group), 
               fill = NA, color = "black", size = 0.8) +
  coord_map()

优化细节说明 #

• 自定义调色板：通过scale_fill_gradientn替换默认填充规则，实现从白色到粉紫色再到深蓝色的渐变效果，完全匹配需求指定的色值。
• 县边界叠加：借助get_county_map获取亚利桑那州的县地理数据，筛选出目标县后，用geom_polygon绘制无填充的边界线，确保与邮编地图坐标系一致。

内容的提问来源于stack exchange，提问作者John Ryan