How to Merge Multiple SpatialPolygonsDataFrames output using for loop in R?

Question

I am calculating shadow cast using Shadow Package in R studio. I have successfully generated shadow cast by the three objects with specific heights for one whole day for every hour. The output I get is a separate shadow for every hour in a separate frame. I wanted to get all shadows in one frame along with the time stamp.

time_seq = seq(from = as.POSIXct("2021-07-19 05:15:00", tz = "Europe/Berlin"), to = as.POSIXct("2021-07-19 21:20:00", tz = "Europe/Berlin"), by = "1 hour")
time_seq
# 
solar_pos_seq = solarpos2(location = location_geo, time = time_seq)
solar_pos_seq
# 
# 
shadow_props = rep(NA, nrow(solar_pos_seq))
shadow_props
# 
for(i in 1:nrow(solar_pos_seq)){
 if(solar_pos_seq[i, 2] < 0) shadow_props[i] = 1 else {
      footprint = shadowFootprint(obstacles = shapefile, obstacles_height_field = "Height", solar_pos = solar_pos_seq[i, , drop = FALSE])
      #plot(footprint)
      footprint
      
      combine_footprint = union(footprint, shapefile)
      complete = union(combine_footprint,settlements)
      plot(complete)

Answer 1

If you put each object in a list element, like this skeleton code:

fList = list()
for(i in 1:10){
  fList[[i]] = sfobject(...i...)
}

Then you need to use rbind to collect the elements together row-wise.

To do this on elements in a list, you can use Reduce:

f123 = Reduce(rbind, fList)

or do.call:

f123 = do.call(rbind, fList)