AddLegend Display Value range instead of percentage when using colorQuantile

问题

I am using R shiny-dashboard to display a weather raster file. I used colorQuantile as the method to display the color. In the legend, it shows the percentage. As you can see in the following image. I want the labels in the legend show the range of the value instead for each bin. I am not sure how to do that.

Here is my server.R

output$weather_map <- renderLeaflet({
        rw = weatherband()

        if (!is.null(rw)) {
            pal_w = colorQuantile('RdYlGn', values(rw), na.color = 'transparent', n = 7)

            leaflet() %>%
                addTiles() %>% 
                addRasterImage(rw, colors = pal_w, opacity = 0.5) %>%
                addLegend(position = 'topright', pal = pal_w, value = raster::values(rw), opacity = 1)            
        }
    })

Note: rw is the raster image.

Thank you in advance!!

回答1:

When I need want to adjust the labels in leaflet I fall back to using the arguments colors and labels instead of pal and values. The upside is you can customize the downside is a few more lines of code.

Since I don't have access to rw I'm grabbing my favorite map example:

library(sf)
nc <- st_read(system.file("shape/nc.shp", package="sf"))

Then the leaflet alternative pattern for customizing the legend labels:

library(leaflet)
qpal <- colorQuantile("RdYlBu", nc$AREA, n = 5)

# the extra code building off the existing pal
qpal_colors <- unique(qpal(sort(nc$AREA))) # hex codes
qpal_labs <- quantile(nc$AREA, seq(0, 1, .2)) # depends on n from pal
qpal_labs <- paste(lag(qpal_labs), qpal_labs, sep = " - ")[-1] # first lag is NA

map %>%
  addPolygons(stroke = FALSE, smoothFactor = 0.2, fillOpacity = 1,
              color = ~qpal(AREA)
  ) %>%
  addLegend(colors = qpal_colors, labels = qpal_labs, opacity = 1)

来源：https://stackoverflow.com/questions/56241152/addlegend-display-value-range-instead-of-percentage-when-using-colorquantile

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colors

Shiny