Question

我在R中使用leaflet创建了一张地图。它是美国的地图，其中多边形是邮政编码级别。我想使用基于某些值的连续调色板为邮政编码着色。我已按照示例here使用colorNumeric函数成功地使用连续颜色映射每个邮政编码，如下所示：

# Create a continuous palette function
library(leaflet)
library(rgdal)
library(dplyr)

# From https://raw.githubusercontent.com/datasets/geo-boundaries-world-110m/master/countries.geojson
countries <- readOGR("json/countries.geojson", "OGRGeoJSON")
map <- leaflet(countries)

pal <- colorNumeric(palette = colorRamp(c('#4575B4', '#D73027', '#FFFFBF'), interpolate="linear"), 
                    domain = countries$gdp_md_est)

map %>%
addPolygons(stroke = FALSE, smoothFactor = 0.2, fillOpacity = 1,
            color = ~pal(gdp_md_est))

这使得复杂的原因是现在我想使用离散调色板分别对邮政编码（基本上替换以前的颜色）进行着色。举个简单的例子，我想使用上面的colorNumeric函数根据平均权重为每个邮政编码着色。然后我会在我的数据中使用另一个邮政编码级别字段，如果我想因某些原因将其排除在外，那么所有邮政编码的多边形都是黑色的，否则会留下原来的颜色。

我发现很难使用leaflet和colorNumeric来实现地图的连续和离散着色。任何帮助将不胜感激！

Answer 1

由于上面的示例不足以进行演示，我决定使用我用于其他传单相关问题的虚拟数据之一。我希望你不介意。根据您的说法，您需要在地图中创建两个图层。一个用于连续变量，另一个用于离散变量。这意味着您需要创建两组颜色。如您所用，您希望将colorNumeric()用于连续变量。您希望将colorFactor()用于离散变量。在我的示例代码中，我创建了一个名为group的新离散变量。完成创建调色板后，您需要绘制地图。您需要使用addPolygons()两次。确保使用group。这将出现在右上角的图层控制按钮中。据我所知，目前我们无法展示一个传奇。我之前遇到过这个问题并得出结论，我们目前别无选择。我希望这个演示足以让你在任务中取得进展。

library(raster)
library(dplyr)
library(leaflet)

# Get UK polygon data
UK <- getData("GADM", country = "GB", level = 2)


### Create dummy data
set.seed(111)
mydf <- data.frame(place = unique(UK$NAME_2),
                   value = sample.int(n = 1000, size = n_distinct(UK$NAME_2), replace = TRUE))

### Create a new dummy column for a discrete variable.
mydf <- mutate(mydf, group = cut(value, breaks = c(0, 200, 400, 600, 800, 1000),
                                 labels = c("a", "b", "c", "d", "e"),
                                 include.lowest = TRUE))


### Create colors for the continuous variable (i.e., value) and the discrete variable.
conpal <- colorNumeric(palette = "Blues", domain = mydf$value, na.color = "black")
dispal <- colorFactor("Spectral", domain = mydf$group, na.color = "black")


leaflet() %>% 
addProviderTiles("OpenStreetMap.Mapnik") %>%
setView(lat = 55, lng = -3, zoom = 6) %>%
addPolygons(data = UK, group = "continuous",
            stroke = FALSE, smoothFactor = 0.2, fillOpacity = 0.3,
            fillColor = ~conpal(mydf$value),
            popup = paste("Region: ", UK$NAME_2, "<br>",
                          "Value: ", mydf$value, "<br>")) %>%
addPolygons(data = UK, group = "discrete",
            stroke = FALSE, smoothFactor = 0.2, fillOpacity = 0.3,
            fillColor = ~dispal(mydf$group),
            popup = paste("Region: ", UK$NAME_2, "<br>",
                          "Value: ", mydf$group, "<br>")) %>%
addLayersControl(overlayGroups = c("continuous", "discrete")) %>%
addLegend(position = "bottomright", pal = conpal, values = mydf$value,
          title = "UK value",
          opacity = 0.3) %>%
addLegend(position = "bottomleft", pal = dispal, values = mydf$group,
          title = "UK group",
          opacity = 0.3)

如果选择连续变量图层，您将看到以下地图。

如果选择离散变量图层，您将看到以下地图。

<强>更新

如果要同时显示连续组和连续组，则需要事先对数据进行子集化，以使多边形不重叠。使用上面的UK和mydf，您可以尝试这样的事情。

### Subset data and create two groups. This is something you gotta do
### in your own way given I have no idea of your own data.

con.group <- mydf[1:96, ]
dis.group <- mydf[97:192, ]


### Create colors for the continuous variable (i.e., value) and the discrete variable.
conpal <- colorNumeric(palette = "Blues", domain = c(min(mydf$value), max(mydf$value)), na.color = "black")
dispal <- colorFactor(palette = "Reds", "Spectral", levels = unique(mydf$group), na.color = "black")


### Subset the polygon data as well

con.poly <- subset(UK, NAME_2 %in% con.group$place)
dis.poly <- subset(UK, NAME_2 %in% dis.group$place)

leaflet() %>% 
addProviderTiles("OpenStreetMap.Mapnik") %>%
setView(lat = 55, lng = -3, zoom = 6) %>%
addPolygons(data = con.poly, group = "continuous",
            stroke = FALSE, smoothFactor = 0.2, fillOpacity = 0.3,
            fillColor = ~conpal(con.group$value),
            popup = paste("Region: ", UK$NAME_2, "<br>",
                          "Value: ", con.group$value, "<br>")) %>%
addPolygons(data = dis.poly, group = "discrete",
            stroke = FALSE, smoothFactor = 0.2, fillOpacity = 0.3,
            fillColor = ~dispal(dis.group$group),
            popup = paste("Region: ", UK$NAME_2, "<br>",
                          "Group: ", dis.group$group, "<br>")) %>%
addLayersControl(overlayGroups = c("continuous", "discrete")) %>%
addLegend(position = "bottomright", pal = conpal, values = con.group$value,
          title = "UK value",
          opacity = 0.3) %>%
addLegend(position = "bottomleft", pal = dispal, values = dis.group$group,
          title = "UK group",
          opacity = 0.3)

宣传单：混合连续和离散的颜色

1 个答案: