validateCoords warns of valid data

[jcheng5]

Polygon/polyline data can be provided as lat/lng vectors with the ring/line groupings indicated by NA values.

# Dummy data
group <- c(219233,219233,167168,167168,208233,208233,219238,219238,145210,145210)
lng <- c(-84.14247,-84.21969,-84.33130,-84.34574,-84.51261,-84.21969,-84.14247,-84.12763,-84.36784,-84.31505)
lat <- c(34.10217,33.95469,34.04140,34.01926,33.91128,33.95469,34.10217,33.95239,33.91493,33.93641)
df <- data.frame(group=group, lng=lng, lat=lat)

# Demo of the problem--all points are considered part of same polyline
library(leaflet)
pal <- colorFactor("Accent", NULL)
leaflet(df) %>% addPolylines(lng = ~lng, lat = ~lat, color = pal(1:5))

# Helper function to split numeric vector with NA, based on a separate group vector
library(purrr)
grouped_coords <- function(coord, group) {
  data.frame(coord = coord, group = group) %>%
    slice_rows("group") %>%
    by_slice(~c(.$coord, NA), .to = "output") %>%
    .$output %>% unlist()
}

# Use the helper function to split the lines
library(leaflet)
pal <- colorFactor("Accent", NULL)
leaflet(df) %>% addPolylines(
  lng = ~grouped_coords(lng, group),
  lat = ~grouped_coords(lat, group),
  color = pal(1:5))

Warning message:
In validateCoords(lng, lat, funcName) :
  Data contains 5 rows with either missing or invalid lat/lon values and will be ignored

[bhaskarvk]

How will you distinguish between this and the case when data is really missing?

[jcheng5]

For this particular format (polygonData.matrix)

1. If all(is.na(lat) != is.na(lng)) then it's an error
2. Two NA in a row is a warning
3. Empty vectors (or only NA vector) is a warning that there's no data

All other formats would behave as they currently do. Does that make sense?

[bhaskarvk]

Yeah I think that sounds about right. I was not aware of the use of NAs for demarkation in polygons.