[R-sig-Geo] Adding great circle routes as polylines in Leaflet

[Ben Tupper]

Hi,

Your example is so close to being reproducible, but not quite close enough.  After some noodling around I figured out that you are using geosphere package in addition to leaflet, and that your tibble is assigned to the `ByRoute` variable.  The following gets you closer - you'll want to resolve the warning messages ... 

Warning messages:
1: In .pointsToMatrix(p2) :longitude > 180
2: In .pointsToMatrix(p2) :longitude > 180
3: In .pointsToMatrix(p2) : longitude > 180


... which you can fix in your tibble.

When adding layers to a map, you really want to create a map object, store it in a variable, say 'm', and ad each layer in an iteration enclosing the pipes (rather than within the pipes).  I'm sure that there will be some wrapping issues if you copy-and-paste from this email.  (Also, please put a bit more white space in your code.  They are calorie-free and make life so much easier on us old fellows.)

Cheers,
Ben


library(leaflet)
library(geosphere)
ByRoute = structure(list(CommencingRegion = c("RedSea", "EastAfrica", "GulfofMexico",
                                        "FarEast", "RedSea", "GulfofMexico"), LoadRegion = c("RedSea",
                                                                                             "RedSea", "GulfofMexico", "FarEast", "RedSea", "GulfofMexico"
                                        ), DischargeRegion = c("NorthWestAfrica", "WestMedditerranean",
                                                               "WestCoastLatinAmerica", "AustraliaNewZealand", "WestMedditerranean",
                                                               "WestCoastCentralAmerica"), Count = c(1L, 1L, 2L, 1L, 2L, 5L),
                   AvgTCE = c(38879.53, 31783.55, 28520.79, 26068.8, 26054.28,
                              25883.81), CLon = c(37.8274879335485, 47.0791103099334, -90.9633701509553,
                                                  146.2727573458, 37.8274879335485, -90.9633701509553), CLat =
                       c(21.4460561443517,
                         -12.9570828789565, 25.2035802054683, 47.6530892619773, 21.4460561443517,
                         25.2035802054683), LLon = c(37.8274879335485, 37.8274879335485,
                                                     -90.9633701509553, 146.2727573458, 37.8274879335485, -90.9633701509553
                         ), LLat = c(21.4460561443517, 21.4460561443517, 25.2035802054683,
                                     47.6530892619773, 21.4460561443517, 25.2035802054683), DLon =
                       c(-17.1597117430475,
                         7.03639948506481, -73.4238157230412, 151.051220297802, 7.03639948506481,
                         255.83509305644), DLat = c(24.2308740597312, 38.8907379374372,
                                                    -25.8934046406896, -25.1880219406131, 38.8907379374372, 21.8130318388702
                         )), row.names = c(NA, -6L), class = c("tbl_df", "tbl", "data.frame"
                         ))



# create the map object
m <- leaflet() %>%
    addTiles() 

# iteratively add each polyline commence-to-load and load-to-destination
for(i in 1:6){
        m <- m %>% 
            addPolylines(data=gcIntermediate(c(ByRoute$CLon[i], ByRoute$CLat[i]), c(ByRoute$LLon[i], ByRoute$CLat[i]),
                                            n=100, addStartEnd = TRUE, sp = TRUE)) %>%
            addPolylines(data=gcIntermediate(c(ByRoute$LLon[i], ByRoute$LLat[i]), c(ByRoute$DLon[i], ByRoute$DLat[i]),
                                             n=100, addStartEnd = TRUE, sp = TRUE))
}        

m      





> On Sep 2, 2018, at 10:34 PM, Dhiraj Khanna <dhirajkhanna using gmail.com> wrote:
> 
> I am trying to add great circle routes between various regions in R. Here’s
> the sample data:
> 
> structure(list(CommencingRegion = c("RedSea", "EastAfrica", "GulfofMexico",
> "FarEast", "RedSea", "GulfofMexico"), LoadRegion = c("RedSea",
> "RedSea", "GulfofMexico", "FarEast", "RedSea", "GulfofMexico"
> ), DischargeRegion = c("NorthWestAfrica", "WestMedditerranean",
> "WestCoastLatinAmerica", "AustraliaNewZealand", "WestMedditerranean",
> "WestCoastCentralAmerica"), Count = c(1L, 1L, 2L, 1L, 2L, 5L),
>    AvgTCE = c(38879.53, 31783.55, 28520.79, 26068.8, 26054.28,
>    25883.81), CLon = c(37.8274879335485, 47.0791103099334, -90.9633701509553,
>    146.2727573458, 37.8274879335485, -90.9633701509553), CLat =
> c(21.4460561443517,
>    -12.9570828789565, 25.2035802054683, 47.6530892619773, 21.4460561443517,
>    25.2035802054683), LLon = c(37.8274879335485, 37.8274879335485,
>    -90.9633701509553, 146.2727573458, 37.8274879335485, -90.9633701509553
>    ), LLat = c(21.4460561443517, 21.4460561443517, 25.2035802054683,
>    47.6530892619773, 21.4460561443517, 25.2035802054683), DLon =
> c(-17.1597117430475,
>    7.03639948506481, -73.4238157230412, 151.051220297802, 7.03639948506481,
>    255.83509305644), DLat = c(24.2308740597312, 38.8907379374372,
>    -25.8934046406896, -25.1880219406131, 38.8907379374372, 21.8130318388702
>    )), row.names = c(NA, -6L), class = c("tbl_df", "tbl", "data.frame"
> ))
> 
> I would like to plot great circle routes between CommencingRegion to
> LoadingRegion and then from LoadingRegion to DischargeRegion for every row.
> Additionally, every row needs to be in a different color and the thickness
> needs to be proportional to AvgTCE. The last 6 variables in the data above
> are the coordinates in Lat Long for the commencing, loading and discharging
> regions respectively. I am quite clueless on how to go about achieving
> this. This is what I have tried and failed:
> 
> leaflet() %>%
>  addTiles() %>%
>  for(i in 1:6){
>    addPolylines(data=gcIntermediate(c(ByRoute$CLon[i],ByRoute$CLat[i]),c(ByRoute$LLon[i],ByRoute$CLat[i]),n=100,addStartEnd
> = T,sp=T))
>  }
> 
> Regards
> Dhiraj Khanna
> Mob:09873263331
> 
> 	[[alternative HTML version deleted]]
> 
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Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org

Ecological Forecasting: https://eco.bigelow.org/