GeoJSON in R Legend - r

Question

I'm trying to create a leaflet plot with each geographical area a specific color based on a property. Here is an test example of my geojson file:
I'm pretty new to geojson and leaflet in general
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {"class": "blah"},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-81.7987060546875,
32.74570253945518
],
[
-81.6229248046875,
32.16631295696736
],
[
-80.958251953125,
32.4263401615464
],
[
-81.2713623046875,
32.791892438123696
],
[
-81.7437744140625,
32.97180377635759
],
[
-81.7987060546875,
32.74570253945518
]
]
]
}
},
{
"type": "Feature",
"properties": {"class": "blah2"},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-82.056884765625,
33.55512901742288
],
[
-81.4471435546875,
33.247875947924385
],
[
-81.40869140625,
33.80653802509606
],
[
-82.078857421875,
33.88865750124075
],
[
-82.40295410156249,
33.58716733904656
],
[
-82.056884765625,
33.55512901742288
]
]
]
}
},
{
"type": "Feature",
"properties": {"class": "blahh3"},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-83.485107421875,
32.930318199070534
],
[
-83.07861328125,
31.863562548378965
],
[
-82.21618652343749,
32.11049589629439
],
[
-82.97973632812499,
33.22030778968541
],
[
-83.726806640625,
33.211116472416855
],
[
-83.485107421875,
32.930318199070534
]
]
]
}
}
]
}
What I want to do is add a legend based off the class properties, such that each different class is associated with a specific color. However, when I try and plot and add the legend I get an error on the plot. Below is my R code:
blahTest <- geojson_read("/file/path/...", what = "sp")
fpal <- colorFactor("viridis", blahTest$class)
leaflet(blahTest) %>%
addTiles() %>%
addPolygons(stroke = FALSE, smoothFactor = 0.3, fillOpacity = 1,
color = ~fpal(class)) %>%
addLegend(colors = ~fpal, opacity = 1.0, labels = ~fpal)

Answer 1

Just some slight modifications to your addLegend argument gives the required output:
# read geojson in r
library(rgdal)
blahTest = readOGR("...", "OGRGeoJSON")
library(leaflet)
# create palette
fpal <- colorFactor(
palette = "viridis",
domain = blahTest$class
)
# plot
leaflet(blahTest) %>%
addTiles() %>%
addPolygons(stroke = FALSE, smoothFactor = 0.3, fillOpacity = 1,
color = ~pal(class)) %>%
addLegend("bottomright",
pal = fpal,
values = ~class,
title = "Legend",
opacity = 1,
labels = ~fpal
)