I want to display a line on a leaflet (for R) map.
The points of my line:
myPoints < - structure(list(lat = c(52.40684, 52.40682, 52.40681, 52.40679,
52.40675, 52.40669, 52.40668, 52.40661, 52.40641, 52.40623, 52.40608,
52.40592, 52.40469, 52.40464, 52.40456, 52.40416, 52.4039, 52.40376,
52.40359, 52.40352, 52.4033, 52.40291, 52.40289, 52.4029, 52.40245,
52.40232, 52.40097, 52.40032, 52.40006, 52.39995, 52.39987, 52.39988,
52.40011, 52.40015, 52.40025, 52.40032, 52.40046, 52.4005, 52.40057,
52.40062, 52.40063, 52.40065, 52.40082, 52.40091, 52.40094, 52.40102,
52.40104, 52.4011, 52.40114, 52.40181, 52.40181, 52.40187, 52.40221,
52.40224, 52.40228, 52.40217, 52.40219, 52.40218, 52.4022, 52.40223,
52.4023, 52.40232, 52.40238, 52.40245, 52.40249, 52.40252, 52.40251,
52.40248, 52.40232, 52.40222, 52.40201, 52.40183, 52.40172, 52.40161,
52.40149, 52.40141, 52.40141, 52.40145, 52.40151, 52.40175, 52.40195,
52.4021, 52.40205, 52.40202, 52.40201, 52.40204, 52.40208, 52.40211,
52.40213, 52.40219, 52.4022, 52.40216, 52.40209, 52.40204, 52.40201,
52.402, 52.40202, 52.40206, 52.40212, 52.4022, 52.40223, 52.40224,
52.40228, 52.4023, 52.40233, 52.40238, 52.40242, 52.40244, 52.40239,
52.40234, 52.40231, 52.40234, 52.40238, 52.4024, 52.40248, 52.4025,
52.40245, 52.40234, 52.4022, 52.4017, 52.40156, 52.4015, 52.40144,
52.40113, 52.40092, 52.40042, 52.39998, 52.39951, 52.3992, 52.39916,
52.39909, 52.39906, 52.39902, 52.39901, 52.39902, 52.39906, 52.39909,
52.39916, 52.39898, 52.39888, 52.39876, 52.39874, 52.39869, 52.39858,
52.398, 52.39712, 52.39685, 52.39612, 52.39575, 52.39574, 52.39562,
52.39559, 52.39558, 52.39549, 52.3953, 52.39512, 52.39505, 52.39478,
52.39463, 52.39451, 52.39281, 52.39277, 52.39267, 52.39258, 52.39247,
52.39242), lng = c(12.97444, 12.97219, 12.97209, 12.97203, 12.97197,
12.97194, 12.97162, 12.97164, 12.97174, 12.97187, 12.97193, 12.97196,
12.97191, 12.97189, 12.97181, 12.97228, 12.97262, 12.97295, 12.97349,
12.97393, 12.97629, 12.98028, 12.98055, 12.98065, 12.98071, 12.98074,
12.98075, 12.98075, 12.98073, 12.98069, 12.98067, 12.98128, 12.98624,
12.98744, 12.99267, 12.99438, 12.99775, 12.99832, 12.9994, 13.00018,
13.0007, 13.00165, 13.00588, 13.00791, 13.00886, 13.009, 13.00909,
13.0101, 13.01094, 13.01086, 13.01101, 13.01239, 13.01235, 13.01316,
13.01429, 13.01431, 13.01493, 13.01502, 13.01519, 13.01521, 13.01523,
13.0153, 13.01579, 13.01596, 13.01602, 13.01607, 13.01623, 13.01632,
13.01657, 13.01709, 13.01778, 13.01812, 13.01823, 13.0183, 13.01836,
13.01839, 13.01857, 13.01976, 13.02107, 13.02707, 13.03184, 13.0357,
13.03572, 13.03578, 13.03593, 13.03599, 13.03602, 13.03602, 13.0367,
13.03808, 13.03829, 13.0383, 13.03835, 13.03844, 13.03856, 13.03868,
13.0388, 13.0389, 13.03897, 13.03901, 13.03901, 13.03924, 13.04057,
13.04103, 13.04104, 13.04108, 13.04113, 13.04128, 13.04142, 13.04146,
13.04147, 13.04194, 13.04295, 13.04346, 13.04519, 13.04547, 13.04555,
13.0457, 13.04589, 13.04663, 13.04689, 13.04698, 13.04701, 13.04717,
13.04729, 13.04755, 13.04774, 13.04786, 13.04801, 13.04802, 13.04795,
13.04788, 13.04766, 13.04759, 13.04766, 13.04788, 13.04795, 13.04802,
13.04811, 13.04818, 13.04833, 13.04842, 13.04842, 13.04842, 13.04843,
13.04841, 13.04839, 13.04825, 13.05091, 13.05121, 13.05225, 13.05242,
13.05254, 13.05251, 13.05242, 13.05229, 13.05259, 13.05487, 13.0561,
13.05704, 13.05646, 13.05654, 13.05735, 13.05803, 13.05881, 13.05924
)), .Names = c("lat", "lng"), row.names = c(NA, -166L), class = "data.frame")
Thats how I make a SpatialLine out of it
makeLine <- function(myMatrix) {
library(sp)
if (nrow(myMatrix) > 1) {
myLine <- Line(myMatrix)
myLinesList <- Lines(list(myLine), 1)
myLineSpatial <- SpatialLines(list(myLinesList))
proj4string(myLineSpatial) <- CRS("+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext +no_defs")
return(myLineSpatial)
} else {
print("Matrix to short")
}
}
After mySpatialLine <- makeLine(myPoints) I have this
class : SpatialLines
features : 1
extent : 52.39242, 52.40684, 12.97162, 13.05924 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs
Which I then try to bring on my leaflet map.
leafletProxy("myMap") %>%
addPolylines(data = mySpatialLine, stroke = TRUE,
fillOpacity = 0.5, smoothFactor = 0.5, layerId = "way"
)
That is not working. Nothing gets displayed. I do not even get an error or warning. Do you have any ideas why?
You assign the wrong coordinate reference system. Your point coordinates are latitude and longitude in degrees, yet you assign a webmercator projection which has units meters. This basically means that the line is too small to be seen, even at the highest zoom level.
Therefore:
makeLine <- function(myMatrix) {
library(sp)
if (nrow(myMatrix) > 1) {
myLine <- Line(myMatrix)
myLinesList <- Lines(list(myLine), 1)
myLineSpatial <- SpatialLines(list(myLinesList))
proj4string(myLineSpatial) <- CRS("+init=epsg:4326")
return(myLineSpatial)
} else {
print("Matrix to short")
}
}
leaflet() %>% addTiles() %>%
addPolylines(data = mySpatialLine, stroke = TRUE,
fillOpacity = 0.5, smoothFactor = 0.5, layerId = "way"
)
should work as intended.