Spatialdataframe from a multipoligon array column

Question

i have a df with a character colum that contains an arrays of wgs84 coordinates.

> head(df$Multipoint)
[1] "[[11.038156,44.525654],[9.768989,45.620678],[7.923145,45.060564]]"                                              
[2] "[[9.768989,45.620678],[11.282019,46.441482],[11.858295,45.651340]]"                                             
[3] "[[11.038156,44.525654],[9.768989,45.620678],[11.126326,43.450791],[11.858295,45.651340]]"                       
[4] "[[11.038156,44.525654],[9.768989,45.620678],[7.923145,45.060564]]"                                              
[5] "[[16.081622,40.499836],[14.840397,40.859856],[12.766940,41.980122],[14.595315,41.684185],[16.619494,40.984473]]"
[6] "[[11.038156,44.525654],[11.126326,43.450791]]" 

As you can observe, there are both points and lines (no polygons). I need to convert it in a spatial dataframe, usually i use

coordinates(object) <- value

but, in this case i need to obtain lines too.

Answer 1

Those arrays look a bit like Javascript arrays, and I suspect you might have got them from a web service, and maybe they are JSON data. This means you can decode them with jsonlite or one of the other JSON packages in R:

> fromJSON("[[11.038156,44.525654],[9.768989,45.620678],[7.923145,45.060564]]")
          [,1]     [,2]
[1,] 11.038156 44.52565
[2,]  9.768989 45.62068
[3,]  7.923145 45.06056

with that saved as coords you can then construct spatial lines objects:

> SpatialLines(list(Lines(list(Line(coords)),ID=1)),proj4string=CRS("+init=epsg:4326"))
class       : SpatialLines 
features    : 1 
extent      : 7.923145, 11.03816, 44.52565, 45.62068  (xmin, xmax, ymin, ymax)
coord. ref. : +init=epsg:4326 +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 
> 

Add a sprinkling of basic R code to work over the rows of your data frame and make a spatial lines data frame, if that's what you need.