Plotting lat long info in dataframe or vector using Leaflet

Question

I have a dataframe which contains a number of columns containing lat long coordinate pairs. I wish to plot these in a map using the leaflet package to see how my data looks.

> str(siteCoor)
'data.frame':   3122 obs. of  18 variables:
 $ Longitude: num  -8.61 -8.61 -8.61 -8.61 -8.61 ...
 $ Latitude : num  52.7 52.7 52.7 52.7 52.7 ...
 $ 1        : num  -8.6 -8.6 -8.6 -8.58 -8.58 ...
 $ 2        : num  52.7 52.7 52.7 52.7 52.7 ...
 $ 3        : num  -8.61 -8.61 -8.61 -8.58 -8.58 ...
 $ 4        : num  52.7 52.7 52.7 52.7 52.7 ...
 $ 5        : num  -8.62 -8.62 -8.62 -8.58 -8.58 ...
 $ 6        : num  52.7 52.7 52.7 52.7 52.7 ...
 $ 7        : num  -8.62 -8.62 -8.62 -8.59 -8.59 ...
 $ 8        : num  52.7 52.7 52.7 52.7 52.7 ...
 $ 9        : num  -8.63 -8.63 -8.63 -8.59 -8.59 ...
 $ 10       : num  52.7 52.7 52.7 52.7 52.7 ...
 $ 11       : num  -8.63 -8.63 -8.63 -8.6 -8.6 ...
 $ 12       : num  52.7 52.7 52.7 52.7 52.7 ...
 $ 13       : num  -8.64 -8.64 -8.64 -8.6 -8.6 ...
 $ 14       : num  52.7 52.7 52.7 52.7 52.7 ...
 $ Longitude: num  -8.61 -8.61 -8.61 -8.61 -8.61 ...
 $ Latitude : num  52.7 52.7 52.7 52.7 52.7 ...

I wish to plot 'Longitude' & 'Latitude', 1&2, 3&4, 5&6, 7&8, 9&10, 11&12, 13&14 and 'Longitude' & 'Latitude' row by row for the entire list. It needs to follow this sequence in order for the polygon to make sense.

Having looked at the help for addPolygons function in R I see that both lat and long need to be in vector format.

Below is the code I am using but when I converted the dataframe to vector format (using double square brackets) I have an error I cannot understand. I also tried using the as.vector function but I could not get it to work.

Could someone please provide a bit of direction?

map <- leaflet() %>%
  addTiles() %>%
  addPolygons(lng=siteCoor[[,c(1,3,5,7,9,11,13,15,17)]],lat=siteCoor[[,c(2,4,6,8,10,12,14,16,18)]])

The error I am receiving when I run this is:

Error in .subset2(x, ..2, exact = exact) : 
  recursive indexing failed at level 2

My data looks as follows:

> head(siteCoor[,c(1,3,5,7,9,11,13,15,17)])
  Longitude         1         3         5         7         9        11        13 Longitude.1
1 -8.609117 -8.602693 -8.609117 -8.615541 -8.621770 -8.627613 -8.632894 -8.637452   -8.609117
2 -8.609117 -8.602693 -8.609117 -8.615541 -8.621770 -8.627613 -8.632894 -8.637452   -8.609117
3 -8.609117 -8.602693 -8.609117 -8.615541 -8.621770 -8.627613 -8.632894 -8.637452   -8.609117
4 -8.609117 -8.578536 -8.580931 -8.584184 -8.588194 -8.592841 -8.597983 -8.603464   -8.609117
5 -8.609117 -8.578536 -8.580931 -8.584184 -8.588194 -8.592841 -8.597983 -8.603464   -8.609117
6 -8.609117 -8.578536 -8.580931 -8.584184 -8.588194 -8.592841 -8.597983 -8.603464   -8.609117

> head(siteCoor[,c(2,4,6,8,10,12,14,16,18)])
  Latitude        2        4        6        8       10       12       14 Latitude.1
1 52.69373 52.71586 52.71620 52.71586 52.71484 52.71319 52.71094 52.70817   52.69373
2 52.69373 52.71586 52.71620 52.71586 52.71484 52.71319 52.71094 52.70817   52.69373
3 52.69373 52.71586 52.71620 52.71586 52.71484 52.71319 52.71094 52.70817   52.69373
4 52.69373 52.70049 52.70361 52.70644 52.70888 52.71085 52.71231 52.71320   52.69373
5 52.69373 52.70049 52.70361 52.70644 52.70888 52.71085 52.71231 52.71320   52.69373
6 52.69373 52.70049 52.70361 52.70644 52.70888 52.71085 52.71231 52.71320   52.69373

What if you write addPolygons(lng=siteCoor[,1],lat=siteCoor[,2]) %>% addPolygons(lng=siteCoor[,3],lat=siteCoor[,4])...? — HubertL
Hi HubertL, I need to plot the rows of the file rather than the columns. If I plot them column by column my map gets messed up. Really I need to take row 1 and pass column 1 and 2 to destPoint and then column 3 and 4, then 5 and 6 and so on and so on until reaching the last lat long pair in column 17 and 18. The destPoint function should then end and then proceed to the next row, row 2 where it begins again. If the function doesn't end, there will be a polygon line drawn from the lat long pair in column 17 and 18 to the new lat long pair in row 2 column 1 and 2. Does this make sense? — TheGoat

HubertL HubertL · Accepted Answer · 2016-10-27T23:34:13

You can try this:

m <- as.matrix(t(siteCoor), byrow=T)
dim(m) <- c(2,length(m)/2)
map <- leaflet() %>% addTiles() %>%
       addPolygons(lng=m[1,],lat=m[2,])

Plotting lat long info in dataframe or vector using Leaflet

1 Answers