How to combine sf_intersects and sf_touches within a function - r
Hi All,
I'm trying to develop a function which maps point coordinates in the UK to the UK local authority areas in which they reside in.
I've developed a function using the st_intersects function of the sf package and it works to identify cases where the centroid intersects with the shapefile of a given area.
However, I also want to identify cases where the centroid actually touches the LA area boundary line.
I'm aware that where LA areas share a boundary this would map the centroid to two LAs but that's ok for my purposes.
I tried to adapt my function to include st_touches however it produces an empty table.
Would be very grateful if someone could take a look and suggest where I might be going wrong.
Reprex below:
The LA area shapefile is publicly available here (the shapefile from the downloads section):
https://geoportal.statistics.gov.uk/datasets/97a614bdcc6043bd9a3cbfbba8a1f302_0/explore?location=55.230176%2C-3.316939%2C6.92
The set of long/lat coordinates to map:
data = structure(list(longitude = c(-2.87481491108804, -2.87127368026435,
-2.96479539064797, -2.92511948140495, -3.01836788419, -2.98402990798746,
-2.9077264274875, -2.89347586558879, -2.97850780890271, -3.02924916756829,
-3.05411812798672, -2.93694678850526, -2.88306663657761, -2.9845903484732,
-3.05984423623939, -2.90909675996297, -2.92181750227365, -3.02464633153093,
-3.02123789197677, -3.09890063032602, -2.96844903903745, -2.86785459942595,
-2.9321154435321, -3.10888230637966, -2.97222428832271, -2.89647987410202,
-3.03027882189321, -2.97866205698605, -2.99429382433499, -3.05246646242959,
-2.89616224682703, -2.98563264041128, -2.95302953391751, -2.91151041579422,
-2.97953110815078, -3.10796669571098, -2.94570764658262, -2.97301831593517,
-2.89323494964768, -2.97063026715387, -2.92198857953645, -3.03675565980253,
-2.83891728241267, -2.91861697258726, -3.06892905484705, -2.99398588944906,
-2.93551831989608, -2.82716052265689, -3.01724727594163, -2.92682901324458,
-2.91803014985187, -2.99284666045525, -2.97786793943296, -2.9230445053825,
-2.95481455034888, -2.93676036122089, -2.96585002429569, -2.86998042564442,
-2.93970334000959, -2.98376964052552, -2.87448694998545, -2.95369805041689,
-2.877566853416, -2.99224636258483, -3.09026039652281, -2.95817525261748,
-2.95017575249327, -2.94359797634677, -2.96710539009414, -3.07792734952214,
-3.17993626061202, -2.97741036119629, -2.95222841522805, -2.95965218909241,
-2.9459062849359, -2.86310994503288, -3.03906859820527, -3.02177819639329,
-2.97166265836844, -3.08145848394861, -3.03808462354296, -2.96263651468074,
-2.95851898803173, -3.02221082538059, -2.89362064147485, -2.8993882625834,
-2.92770961205626, -2.96369118745873, -2.89571920584541, -3.09314291426038,
-3.0919937117765, -3.03611523902419, -2.93117415659881, -2.97460696743252,
-2.85036432827623, -2.94987226425819, -2.95390181653767, -2.91019481240696,
-2.99966589456369, -2.93169619777761, -3.08411731249804, -3.1706199707398,
-2.91896769518433, -2.97090655977713, -3.11395127242533, -3.04781510226649,
-3.18378788354865, -2.90075209953503, -2.93948388571496, -2.98732033573349,
-2.96611890948035, -2.87803392597212, -3.02717324311628, -2.90642650501013,
-3.0181126772633, -2.98716889544258, -2.95609545040814, -2.89457583588837,
-2.9183348068514, -2.88807533717785, -3.02947911076491, -2.98582946684398,
-2.90956913387858, -2.92612896591959, -2.8618485532865, -2.93181934586936,
-2.99086525128266, -2.88799987536917, -3.18188458893135, -2.92530589829918,
-2.84517946221428, -3.02066308251878, -2.943131290944, -2.9316549262618,
-2.89416059133544, -3.03093156077094, -3.03954865354919, -3.02892322932484,
-3.15157580297919, -2.97019350603118, -2.95926518021845, -3.12995261693527,
-3.0178786559463, -2.96998299026556, -2.92983501387733, -2.91526010044323,
-2.98893750456704, -2.93303968342649, -2.97826195863277, -3.10231870679243,
-2.86918162475871, -2.94860479427078, -2.89593919501248, -3.04120959095772,
-3.08974718532665, -3.05135478822517, -2.98129768711627, -3.03665798566578,
-2.89429626072004, -2.92008555617904, -2.87339557195832, -2.89374834459854,
-2.97879863154011, -2.95902409390154, -2.8950914531408, -2.96902081781808,
-2.95976145407803, -2.92255923707144, -3.05150511302466, -3.05903671872711,
-2.95262009289705, -3.00863929575895, -3.0547892173777, -3.03276242335601,
-2.84477534615073, -3.11863250997746, -3.03915412086859, -2.93123288923061,
-3.11376765617702, -3.15438194594307, -3.02283334806073, -2.95561312619315,
-3.02508648595712, -3.15483442747855, -2.96632534070746, -2.98706717919529,
-2.86455911629215, -2.97919924773756, -3.14477357952329, -2.91786092204208,
-3.048045603786, -2.92396930828526, -2.87962098053312, -2.93684151727313,
-3.11262802664107, -2.90201460498108, -2.94757682014421, -2.97896151794228,
-2.98981135039931, -2.95833097373606), latitude = c(53.4379570197908,
53.4201221364593, 53.3942986189115, 53.3842844842061, 53.3617791885161,
53.4151651024398, 53.4508620255715, 53.3939173214826, 53.4064101823484,
53.3718255079932, 53.4378662280985, 53.4375126675335, 53.4206467370139,
53.4029535199428, 53.4259950343029, 53.4140285695349, 53.3888028546485,
53.3879553701277, 53.383130581584, 53.3980816902538, 53.4094946698524,
53.4280841646817, 53.4251728245991, 53.4065738999879, 53.4338598436095,
53.4259310929223, 53.3889496585032, 53.3412480513966, 53.4088327587453,
53.4282695483082, 53.3714698780691, 53.3992414758791, 53.4283426004897,
53.3694659558339, 53.4034617561608, 53.3852333876622, 53.4307199421458,
53.4145901432611, 53.3443452440954, 53.3896653425554, 53.408541145569,
53.4215685101068, 53.3869120986626, 53.3861128798233, 53.4347861533497,
53.4001430176595, 53.3902962809302, 53.3444171680078, 53.3626786684076,
53.3737795084725, 53.4356820437825, 53.4061211555453, 53.4062807459519,
53.4440809390267, 53.4300901595633, 53.4454602665698, 53.4136326339338,
53.3744591704793, 53.4266774115989, 53.4103300396462, 53.4245895519719,
53.4252630671781, 53.4012893604736, 53.4258121557628, 53.3283517163451,
53.4296137958026, 53.3894613832297, 53.3911944946134, 53.4311598021066,
53.4019404403309, 53.3660259655574, 53.4066620280597, 53.4052301130645,
53.4610898898285, 53.3834008004254, 53.396693596265, 53.3732415469181,
53.3830899845843, 53.4145203148397, 53.384011307051, 53.385933567503,
53.4418746881753, 53.3893676837379, 53.3754186100903, 53.3477042237358,
53.4268260826889, 53.4529736611373, 53.4009301384742, 53.4255412928395,
53.3799946476186, 53.3832592444011, 53.4280280487181, 53.4371892773805,
53.3873993179818, 53.387265880647, 53.4311902629893, 53.4000835375925,
53.416299149301, 53.3472942931141, 53.4335267442322, 53.3780004976281,
53.3901906552793, 53.3856427565351, 53.4064274548061, 53.3915868687672,
53.3988915899388, 53.38243801477, 53.3582036174684, 53.4310567146736,
53.4071737491274, 53.4613164150686, 53.4509761373123, 53.3767513171219,
53.4386111541956, 53.3813234955064, 53.4115730142442, 53.4690375638476,
53.3925877169023, 53.4149064630925, 53.4378681311582, 53.363283937878,
53.3439845549594, 53.3919170930087, 53.4003921305836, 53.3729720867359,
53.3971837533247, 53.4043577837836, 53.4356933993701, 53.3940528400041,
53.4497743100287, 53.3896667782373, 53.4087450666446, 53.4421561637244,
53.4419585659703, 53.3476642223286, 53.3773841273259, 53.4318096029357,
53.359549289032, 53.3954996343164, 53.4603395616878, 53.3790873492044,
53.3995806276861, 53.3923100412117, 53.4610154343059, 53.4344581137143,
53.4181570758271, 53.4185223637193, 53.3972820875749, 53.402475229261,
53.4081268716824, 53.4237868466879, 53.3959009588377, 53.4045147184146,
53.4117047911735, 53.3747671044637, 53.4265465099582, 53.3173604267677,
53.3853886811948, 53.4071671211117, 53.4458146150033, 53.4509562137809,
53.3545258760886, 53.4081608055445, 53.4639623704057, 53.4066875108909,
53.4326544056812, 53.3958027859543, 53.378011861023, 53.4143471677853,
53.3916913284024, 53.3831046999105, 53.3526121691896, 53.424242035722,
53.4170165452222, 53.3426757282892, 53.3946264472929, 53.4299953680367,
53.3730800431989, 53.3787971976028, 53.3974951074273, 53.3894123258524,
53.4079890811827, 53.3898479198151, 53.4014279834277, 53.4445415555092,
53.4092342886507, 53.3858335487274, 53.4380366162007, 53.4083295907901,
53.4145595413981, 53.4247867968646, 53.4332901497374, 53.4017057070297,
53.4238324512685, 53.3875542058095, 53.3639110429771, 53.4288174617707,
53.3844646095652, 53.4258501205813, 53.4004076184837)), row.names = c(NA,
-200L), class = c("tbl_df", "tbl", "data.frame"))
Loading the shapefile
library(dplyr)
library(data.table)
library(sf)
library(purrr)
shapefile <- sf::read_sf("downloads/LAD_MAY_2021_UK_BFC.shp")
The function with st_intersects only (works):
getBuildings <- function(data, shapefile) {
shapefile <- sf::st_transform(shapefile, crs = 4326)
pnts_sf <- sf::st_as_sf(data, coords = c('longitude', 'latitude'), crs = sf::st_crs(shapefile))
locations_by_area<- pnts_sf %>%
dplyr::mutate(
intersection = as.integer(sf::st_intersects(geometry, shapefile$geometry))
, LAD21NM = dplyr::if_else(is.na(intersection), '', shapefile$LAD21NM[intersection])
) %>%
data.table::setDT() %>%
dplyr::mutate(latitude = unlist(purrr::map(geometry,2)),
longitude = unlist(purrr::map(geometry,1)))
locations_by_area
}
results = getBuildings(data = data, shapefile = shapefile)
The function with st_touches (doesn't provide any results):
getBuildings <- function(data, shapefile) {
shapefile <- sf::st_transform(shapefile, crs = 4326)
pnts_sf <- sf::st_as_sf(data, coords = c('longitude', 'latitude'), crs = sf::st_crs(shapefile))
locations_by_area<- pnts_sf %>%
dplyr::mutate(
intersection = as.integer(sf::st_intersects(geometry, shapefile$geometry))
touch = as.integer(sf::st_touches(geometry, shapefile$geometry))
, LAD21NM = dplyr::if_else(is.na(intersection), '', shapefile$LAD21NM[intersection])
, LAD21NM2 = dplyr::if_else(is.na(touch), '', shapefile$LAD21NM[touch])
) %>%
data.table::setDT() %>%
dplyr::mutate(latitude = unlist(purrr::map(geometry,2)),
longitude = unlist(purrr::map(geometry,1)))
locations_by_area
}
results = getBuildings(data = data, shapefile = shapefile)
The end result I'm looking for is a table of the original coordinates with another column indicating which LA area they reside in and another column indicating which LA the centroid touches the border of (I'm guessing there would be two rows for some centroids where they touch a border shared by two LA areas).
Any help would be greatly appreciated, please and thank you.
Related
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It appears something was expected to happen with the following line of code. But that something is not happening. point_sf <- st_as_sf(point_df, coords = c("longitude", "latitude")) While this line of code creates the simple feature geometric point objects, this code does not create the simple feature geometry column (sfc) object. And since there is no sfc object, the next line of code does not work. point_sf <- st_set_crs(point_sf, 4326) In this other line of code, the function, st_set_crs(), retrieves a coordinate reference system from sf or sfc objects. But neither the sf or the sfc objects currently exist. Therefore, the sfc object must be first created before using the function: st_set_crs(). It really helps to follow the following steps whenever doing these types of simple feature projects. x.sfg <- st_multipoint(c(lon,lat), dim = "XY") # create sf geometry from lon/lat x.sfc <- st_sfc(x.sfg, crs = 4326) # create sfc from geometry x.sf <- st_sf(df, x.sfc) # create sf object from sfc First convert the log and lat to vectors, then create the matrix, and then create the simple feature objects in the correct progression. lon <- c(-81.5190053, -73.7562317, -73.9395687, -106.650422, -75.4714098, -75.3704579, -84.3879824, -82.0105148, -97.7430608, -119.0187125) lat <- c(41.0814447, 42.6525793, 42.8142432, 35.0843859, 40.6022939, 40.6259316, 33.7489954, 33.4734978, 30.267153, 35.3732921) m <- matrix(data = c(lon, lat), nrow = 10, ncol = 2, byrow = FALSE) m.sfg <- st_multipoint(m, dim = "XY") m.sfc <- st_sfc(m.sfg, crs = 4326) m.sf <- st_sf(df, m.sfc) head(m.sf, 3) Then create a base plot of the continental US, and then plot the simple feature object onto the base map. plot(US_48, axes = TRUE) plot(m.sf, add= TRUE, pch = 19, col = "red") The link shown above with the question does not seem to have anything related to this question. The answer shown here does not convert the sf object into sp then change back to sf. The plot is shown at link:
Using R to identify nearest point to a location and calculate the distance between them along a network/road
I have a series of locations (Points_B) and would like to find the closest point to them from a different set of points (Points_A) and the distance between them in kms. I can do this as the crow flies but cannot work out how to do the same along a road network (the 'Roads' object in the code). The code I have so far is a follows: library(sp) library(rgdal) library(rgeos) download.file("https://dl.dropboxusercontent.com/u/27869346/Road_Shp.zip", "Road_Shp.zip") #2.9mb unzip("Road_Shp.zip") Roads <- readOGR(".", "Subset_Roads_WGS") Points_A <- data.frame(ID = c("A","B","C","D","E","F","G","H","I","J","K","L"), ID_Lat = c(50.91487, 50.92848, 50.94560, 50.94069, 50.92275, 50.94109, 50.92288, 50.92994, 50.92076, 50.90496, 50.89203, 50.88757), ID_Lon = c(-1.405821, -1.423619, -1.383509, -1.396910, -1.441801, -1.459088, -1.466626, -1.369458, -1.340104, -1.360153, -1.344662, -1.355842)) rownames(Points_A) <- Points_A$ID Points_B <- data.frame(Code = 1:30, Code_Lat = c(50.92658, 50.92373, 50.93785, 50.92274, 50.91056, 50.88747, 50.90940, 50.91328, 50.91887, 50.92129, 50.91326, 50.91961, 50.91653, 50.90910, 50.91432, 50.93742, 50.91848, 50.93196, 50.94209, 50.92080, 50.92127, 50.92538, 50.88418, 50.91648, 50.91224, 50.92216, 50.90526, 50.91580, 50.91203, 50.91774), Code_Lon = c(-1.417311, -1.457155, -1.400106, -1.374250, -1.335896, -1.362710, -1.360263, -1.430976, -1.461693, -1.417107, -1.426709, -1.439435, -1.429997, -1.413220, -1.415046, -1.440672, -1.392502, -1.459934, -1.432446, -1.357745, -1.374369, -1.458929, -1.365000, -1.426285, -1.403963, -1.344068, -1.340864, -1.399607, -1.407266, -1.386722)) rownames(Points_B) <- Points_B$Code Points_A_SP <- SpatialPoints(Points_A[,2:3]) Points_B_SP <- SpatialPoints(Points_B[,2:3]) Distances <- (gDistance(Points_A_SP, Points_B_SP, byid=TRUE))*100 Points_B$Nearest_Points_A_CF <- colnames(Distances)[apply(Distances,1,which.min)] Points_B$Distance_Points_A_CF <- apply(Distances,1,min) The output I am after would be two additional columns in 'Points_B' with 1) having the nearest Point A object ID along the road network and 2) having the distance along the network in km. Any help would be appreciated. Thanks.
I've been working on this kind of problem all day. Try mapdist() in the ggmap package and see if this works: library(dplyr) library(ggmap) #Your data Points_A <- data.frame(ID = c("A","B","C","D","E","F","G","H","I","J","K","L"), ID_Lat = c(50.91487, 50.92848, 50.94560, 50.94069, 50.92275, 50.94109, 50.92288, 50.92994, 50.92076, 50.90496, 50.89203, 50.88757), ID_Lon = c(-1.405821, -1.423619, -1.383509, -1.396910, -1.441801, -1.459088, -1.466626, -1.369458, -1.340104, -1.360153, -1.344662, -1.355842)) Points_B <- data.frame(Code = 1:30, Code_Lat = c(50.92658, 50.92373, 50.93785, 50.92274, 50.91056, 50.88747, 50.90940, 50.91328, 50.91887, 50.92129, 50.91326, 50.91961, 50.91653, 50.90910, 50.91432, 50.93742, 50.91848, 50.93196, 50.94209, 50.92080, 50.92127, 50.92538, 50.88418, 50.91648, 50.91224, 50.92216, 50.90526, 50.91580, 50.91203, 50.91774), Code_Lon = c(-1.417311, -1.457155, -1.400106, -1.374250, -1.335896, -1.362710, -1.360263, -1.430976, -1.461693, -1.417107, -1.426709, -1.439435, -1.429997, -1.413220, -1.415046, -1.440672, -1.392502, -1.459934, -1.432446, -1.357745, -1.374369, -1.458929, -1.365000, -1.426285, -1.403963, -1.344068, -1.340864, -1.399607, -1.407266, -1.386722)) #Combine coords into one field (mapdist was doing something funny with the commas so I had to specify "%2C" here) Points_A$COORD <- paste(ID_Lat, ID_Lon, sep="%2C") Points_B$COORD <- paste(Code_Lat, Code_Lon, sep="%2C") #use expand grid to generate all combos get_directions <- expand.grid(Start = Points_A$COORD, End = Points_B$COORD, stringsAsFactors = F, KEEP.OUT.ATTRS = F) %>% left_join(select(Points_A, COORD, ID), by = c("Start" = "COORD")) %>% left_join(select(Points_B, COORD, Code), by = c("End" = "COORD")) #make a base dataframe route_df <- mapdist(from = get_directions$Start[1], to = get_directions$End[1], mode = "driving") %>% mutate(Point_A = get_directions$ID[1], Point_B = get_directions$Code[1]) #get the rest in a for-loop start <- Sys.time() for(i in 2:nrow(get_directions)){ get_route <- mapdist(from = get_directions$Start[i], to = get_directions$End[i], mode = "driving") %>% mutate(Point_A = get_directions$ID[i], Point_B = get_directions$Code[i]) route_df <<- rbind(route_df, get_route) #add to your original file Sys.sleep(time = 1) #so google doesn't get mad at you for speed end <- Sys.time() print(paste(i, "of", nrow(get_directions), round(i/nrow(get_directions),4)*100, "%", sep=" ")) print(end-start) } #save if you want write.csv(route_df, "route_df.csv", row.names = F) #Route Evaluation closest_point <-route_df %>% group_by(Point_A) %>% filter(km == min(km)) %>% ungroup() I'm still kind of new at this so there may be a better way to do the data wrangling. Hope this helps & good luck
The packages igraph, osmr and walkalytics all seem to provide this functionality these days. Mode-specific routing networks exist (in various degrees of functionality).
Minimum elevation within km
Trying to find the minimum elevation within 10km of a certain latitude and longitude using R. So far I have dem <- getData("SRTM", lat=42.90, lon=-78.85, path = datadir) plot(dem) I know I need to create spatial points and eventually buffer/extract the information. When I try: buffdem <- buffer(dem, width=10000) It does not work because I don't have any points. I tried dem <- getData("SRTM", lat=42.90, lon=-78.85, path = datadir) coords <- data.frame( x = rnorm(100), y = rnorm(100) ) coordinates(dem) spdf = SpatialPointsDataFrame(coords, dem) I get the following error: Error in validObject(.Object) : invalid class “SpatialPointsDataFrame” object: invalid object for slot "data" in class "SpatialPointsDataFrame": got class "RasterLayer", should be or extend class "data.frame"
I think this accomplishes what you need: library(raster) #elevation <- getData("SRTM", lat=42.90, lon=-78.85) #poi <- cbind(lon=-78.85, lat=42.90) using a smaller example data set for quicker download: elevation <- getData('alt', country='CHE') poi <- cbind(8.13, 46.47) e <- extract(elevation, poi, buffer=10000) sapply(e, min, na.rm=TRUE) By the way, this is a duplicate of this and this question.