Assign data to nearest sampling point in R

Question

I'm very new to R and would like to get help with assigning data point (data set 1) to the nearest sampling point (data set 2). The sampling points are equally spaced along a line at 100-m intervals, and the data points were taken along this line. My aim to generate a csv file with the nearest sampling point assigned to each data point. Both my data and sampling points are data frames.

Here is my code:

sampling.points <- read.csv("pts.csv",header=T)

data <- read.csv("data.csv",header=T)

library("sf")

sp_sf <- st_as_sf(sampling.points, coords = c("x", "y"), crs = 24500, agr="NA_agr_")

data_sf = st_as_sf(data, coords = c("x", "y"), crs = 24500, agr = "NA_agr_")

library("nngeo")

st_nn(x, y, sparse = TRUE, k = 1, maxdist = 100,
      returnDist = FALSE, progress = TRUE)

I have managed to generate all until the last sentence - An error code returned which I'm unable to understand:

Error in UseMethod("st_geometry") : no applicable method for 'st_geometry' applied to an object of class "c('matrix', 'double', 'numeric')".

Appreciate if someone can help me with this.

sampling.points <- structure(list(point = structure(1:10, .Label = c("TC01", "TC02",  "TC20", "TC21", "TC22",
"TC23", "TC24", "TC25", "TC26", "TC27",  "TC28", "TC29", "TC30",
"TC31", "TC32", "TD01", "TD02", "TD06",  "TD07", "TD08", "TD09",
"TD10", "TD11", "TD12", "TD13", "TQ25",  "TQ26", "TQ27", "TQ28",
"TQD02", "TQD03", "TQD04"), class = "factor"), 
 y = c(1.34285, 1.34314, 1.34373, 1.34416, 1.34457, 1.34502, 
 1.34543, 1.34586, 1.34575, 1.34593), x = c(103.7791, 103.7789, 
 103.7787, 103.7787, 103.7788, 103.7789, 103.7791, 103.7792, 
 103.7787, 103.7784)), row.names = c(NA, 10L), class = "data.frame")

data <- structure(list(point = structure(c(2L, 19L, 6L, 7L, 16L, 16L,  18L, 4L, 7L, 10L), .Label = c("CH651", "CH652",
 "CH653", "CH654",  "CH655", "CH656", "CH657", "CH658", "CH659",
 "CH660", "CH661",  "CH662", "CH663", "CH664", "CH665", "CH666",
 "CH667", "CH668",  "CH669", "CH670", "CH671", "CH672", "CH673",
 "CH674", "CH675",  "CH676", "CH677", "CH678", "CH679", "CH680",
 "CH681", "CH682",  "CH683", "FQ419", "FQ420", "FQ421", "FQ422",
 "FQ423", "FQ424",  "FQ425", "FQ426", "FQ427", "FQ428", "FQ429",
 "FQ430", "FQ431",  "FQ432", "FQ433", "FQ434", "FQ435", "FQ436",
 "FQ437", "JT4490",  "JT4491", "JT4492", "JT4493", "JT4494", "JT4495",
 "JT4496", "JT4497",  "JT4498", "JT4499", "JT4500", "JT4501", "JT4502",
 "JT4503", "JT4504",  "JT4505", "JT4506", "JT4507", "JT4508", "JT4509",
 "JT4510", "JT4511",  "JT4512", "JT4513", "JT4514", "JT4515"), class =
 "factor"), x = c(1.345922006, 
 1.34295498, 1.346109007, 1.345989984, 1.344331037, 1.344331037, 
 1.343491003, 1.346088974, 1.345989984, 1.345756967), y = c(103.776551, 
 103.778987, 103.777546, 103.777906, 103.778766, 103.778766, 103.778702, 
 103.777206, 103.777906, 103.779213), taxon = structure(c(3L,  3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), .Label = c("#N/A", "Amphibian",  "Bird",
 "Butterfly", "Mammal", "Odonate", "Reptile"), class = "factor"), 
     scientific_name = structure(c(2L, 2L, 3L, 4L, 4L, 5L, 5L, 
     6L, 6L, 6L), .Label = c("Accipiter sp.", "Acridotheres javanicus", 
     "Aegithina tiphia", "Aerodramus sp.", "Aethopyga siparaja", 
     "Aplonis panayensis", "Bronchocela cristatella", "Callosciurus notatus", 
     "Caprimulgus macrurus", "Caprimulgus sp.", "Chalcorana labialis", 
     "Chrysophlegma miniaceum", "Cinnyris jugularis", "Cratilla metallica", 
     "Cupha erymanthis lotis", "Curetis santana malayica", "Cynopterus brachyotis", 
     "Dicaeum cruentatum", "Dicaeum sp.", "Dicaeum trigonostigma", 
     "Dicrurus paradiseus", "Dinopium javanense", "Duttaphrynus melanostictus", 
     "Elymnias hypermnestra agina", "Eooxylides tharis distanti", 
     "Eudynamys scolopaceus", "Eurema sari sodalis", "Eurema sp.", 
     "Flying squirrel sp.", "Galeopterus variegatus", "Gallus gallus", 
     "Gracula religiosa", "Graphium sp.", "Ideopsis vulgaris macrina", 
     "Insect bat", "Insect Bat", "Jamides bochus nabonassar", 
     "Lexias pardalis dirteana", "Limnonectes plicatellus", "Loriculus galgulus", 
     "Macaca fascicularis", "Macronus gularis", "Microhyla butleri", 
     "Microhyla heymonsi", "Muscicapa dauurica", "Muscicapa sibirica", 
     "Mycalesis visala phamis", "Nacaduba sp.", "Nyctixalus pictus", 
     "Oriolus chinensis", "Orthetrum glaucum", "Orthotomus atrogularis", 
     "Orthotomus sericeus", "Orthotomus sutorius", "Otus lempiji", 
     "Paradoxurus musangus", "Phylloscopus borealis", "Polypedates leucomystax", 
     "Polyura hebe plautus", "Psilopogon lineatus", "Psittacula longicauda", 
     "Pulchrana laterimaculata", "Pycnonotus plumosus", "Rallina fasciata", 
     "Rattus sp.", "Rattus sp. ", "Sundasciurus tenuis", "Sus scrofa", 
     "Tanaecia pelea pelea", "Treron vernans", "Tyriobapta torrida", 
     "Zosterops simplex"), class = "factor"), local_status = structure(c(7L, 
     7L, 7L, 1L, 1L, 7L, 7L, 7L, 7L, 7L), .Label = c("#N/A", "Critically Endangered", 
     "Endangered", "Least Concern", "Not Assessed", "Not listed", 
     "Not Listed", "Vulnerable"), class = "factor"), indivs = c(1L, 
     6L, 1L, 2L, 1L, 1L, 1L, 2L, 10L, 100L), seen_heard = structure(c(2L, 
     2L, 1L, 2L, 2L, 1L, 2L, 1L, 2L, 2L), .Label = c("Heard", 
     "Seen"), class = "factor"), method = structure(c(2L, 2L, 
     2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("Incidental", 
     "Transect"), class = "factor")), row.names = c(NA, 10L), class = "data.frame")