R语言中Mapview点未全显及st_buffer区域合并的问题解决
2026-6-25
问题：mapview采样点显示不全及st_buffer缓冲区合并异常
使用mapview构建地图时遇到两个问题：
- 用
st_sample生成的10个采样点，仅部分能在mapview中显示；但用plot()函数绘图时，所有点都能正常显示。 st_buffer生成的缓冲区会将本该独立的区域合并，该问题在mapview和plot绘图中均存在。
重现代码
library(sf) library(mapview) library(magrittr) set.seed(145) chemins.32188 = st_zm(chemins2) %>% st_transform(crs = 32188) rd.pts.sentiers <- st_sample(x = chemins.32188, size = 10) buff.pt = st_buffer(x = rd.pts.sentiers, dist = units::set_units(x = 100, value = "m")) mapviewOptions(fgb = FALSE) mapview(chemins.32188) + mapview(rd.pts.sentiers) + mapview(buff.pt)
mapview绘图效果：仅显示部分红色采样点，蓝色缓冲区存在明显的区域合并现象。
plot绘图代码
plot(chemins.32188$geom) plot(buff.pt, add= TRUE, col = scales::alpha("blue", .5)) plot(rd.pts.sentiers, add= TRUE, pch = 19, col = "red")
plot绘图效果：所有红色采样点均正常显示，但蓝色缓冲区的区域合并问题依然存在。
数据结构
chemins2 = structure(list(Name = "Path Measure", description = NA_character_, timestamp = structure(NA_real_, class = c("POSIXct", "POSIXt" )), begin = structure(NA_real_, class = c("POSIXct", "POSIXt" )), end = structure(NA_real_, class = c("POSIXct", "POSIXt" )), altitudeMode = NA_character_, tessellate = -1L, extrude = 0L, visibility = -1L, drawOrder = NA_integer_, icon = NA_character_, sentier = NA_character_, layer = "path Parc — Path Measure", path = "~/Desktop/path Parc.kml|layername=Path Measure|geometrytype=LineString25D|uniqueGeometryType=yes", geom = structure(list(structure(list(structure(c(299434.130314458, 300531.43655987, 299434.130314458, 5046816.92873926, 5047257.53966348, 5046816.92873926), dim = 3:2), structure(c(299434.130314458, 300401.157828111, 299434.130314458, 5046816.92873926, 5046249.12770288, 5046816.92873926), dim = 3:2)), class = c("XY", "MULTILINESTRING", "sfg"))), n_empty = 0L, crs = structure(list(input = "EPSG:32188", wkt = "PROJCRS[\"NAD83 / MTM zone 8\",\n BASEGEOGCRS[\"NAD83\",\n DATUM[\"North American Datum 1983\",\n ELLIPSOID[\"GRS 1980\",6378137,298.257222101,\n LENGTHUNIT[\"metre\",1]]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4269]],\n CONVERSION[\"MTM zone 8\",\n METHOD[\"Transverse Mercator\",\n ID[\"EPSG\",9807]],\n PARAMETER[\"Latitude of natural origin\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8801]],\n PARAMETER[\"Longitude of natural origin\",-73.5,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9999,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",304800,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8806]],\n PARAMETER[\"False northing\",0,\n LENGTHUNIT[\"metre\",1],\n ID[\"EPSG\",8807]]],\n CS[Cartesian,2],\n AXIS[\"easting (E(X))\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"northing (N(Y))\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"Engineering survey, topographic mapping.\"],\n AREA[\"Canada - Quebec between 75°W and 72°W.; Canada - Ontario - east of 75°W.\"],\n BBOX[44.98,-75,62.53,-72]],\n ID[\"EPSG\",32188]]"), class = "crs"), class = c("sfc_MULTILINESTRING", "sfc"), precision = 0, bbox = structure(c(xmin = 299434.130314458, ymin = 5046249.12770288, xmax = 300531.43655987, ymax = 5047257.53966348 ), class = "bbox"))), row.names = 1L, sf_column = "geom", agr = structure(c(Name = NA_integer_, description = NA_integer_, timestamp = NA_integer_, begin = NA_integer_, end = NA_integer_, altitudeMode = NA_integer_, tessellate = NA_integer_, extrude = NA_integer_, visibility = NA_integer_, drawOrder = NA_integer_, icon = NA_integer_, sentier = NA_integer_, layer = NA_integer_, path = NA_integer_), class = "factor", levels = c("constant", "aggregate", "identity")), class = c("sf", "data.frame"))
内容的提问来源于stack exchange，提问作者M. Beausoleil
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