Change LineString style for leaflet map with R shiny - r

Question

I have a leaflet map in R with a lot of LineStrings in it. The lines default to blue, with a certain thickness. I want to change the line color and have the thickness depend on a weight variable. I create the map by reading a geojson file. Adding a "style" section directly to each linestring feature in the geojson isn't working. Here is my R code for the map:
colchoice = "red"
ptl_str = paste("#! function(feature, latlng){
return L.circleMarker(latlng, {
radius: feature.properties.radius || 5,
fillColor: feature.properties.fillColor || '", colchoice, "',
color: '#000',
weight: 1,
fillOpacity: 0.8
})
} !#", sep="")
m <- Leaflet$new()
m$setView(c(38.892682, -77.031681), zoom = 12)
m$geoJson(geojson,
onEachFeature = "#! function(feature, layer){
layer.bindPopup(feature.properties.popup)
} !#",
pointToLayer = ptl_str)
m
This successfully formats points on the map into dots. But now I want to format the lines differently too. I appreciate any help. Thanks!

Answer 1

Upfront: i know nothing about R and not able to test what i'm saying, but i know my way around Leaflet in Javascript and can tell you how i would go about accomplishing that in JS, so you can translate it to R:
var geoJsonLayer = L.geoJson(data, {
onEachFeature: function (feature, layer) {
if (layer instanceof L.Polyline) {
layer.setStyle({
'color': feature.properties.color
});
}
}
});
Here's a working example on Plunker: http://plnkr.co/edit/g4juen?p=preview