我有一个包含线的简单要素数据集，我尝试使用sf包和R查找距离各自端点超过30m的线部分。这是我最初尝试的：
library(tidyverse)
library(sf)
lines = lines |>
mutate(geom = st_cast(x = geometry, to = "LINESTRING"))|> #Make sure all geoms are Linestrings
mutate(edges = st_line_sample(x = geom, sample = c(0,1)))|> #Find Endpoints of every line
mutate(buff = st_buffer(edges, dist = 30)) |> #30m Buffer around Endpoints
mutate(geom = st_difference(x = geom, y = buff)) #Error! Creates more geoms that expected但是，最后一行会产生以下错误：geom的大小必须是897或1，而不是804206。我希望它能准确地生成几何体的数量，因为数据集中有行。然而，从错误消息st_difference（）判断，它生成了更多的几何体。我想我在mutate（）和st_differnce（）如何结合使用方面有些错误。
我使用了以下变通方案：
lines = lines |>
mutate(geom = st_cast(x = geometry, to = "LINESTRING"))|> #Make sure all geoms are Linestrings
mutate(edges = st_line_sample(x = geom, sample = c(0,1)))|> #Find Endpoints of every line
mutate(buff = st_buffer(edges, dist = 30)) #30m Buffer around Endpoints
# mutate(geom = st_difference(x = geom, y = buff)) #Error! Creates more geoms that expected
#Workaround:
hed = st_difference(x = lines #Remove parts of hedges that are
y = st_union(lines$buff)) #within 30m of an Endpoint.但这并不完全是我要找的，因为它也会删除靠近其他线端点的部分线，但我只想删除距离自己端点30米以内的部分线。
下面是我的数据集中的一些示例数据，以提高可重复性（抱歉，这里很乱）：
lines = structure(list(id = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1), geometry = structure(list(
structure(c(599534.62516477, 599554.318937559, 5764376.16380116,
5764315.9767656), dim = c(2L, 2L), class = c("XY", "LINESTRING",
"sfg")), structure(c(599590.720979866, 599682.072092792,
5764201.56638851, 5763913.81271676), dim = c(2L, 2L), class = c("XY",
"LINESTRING", "sfg")), structure(c(599685.38979868, 599731.651412595,
5763901.42515664, 5763751.07786744), dim = c(2L, 2L), class = c("XY",
"LINESTRING", "sfg")), structure(c(599464.01445783, 599384.800422916,
599356.793826265, 599342.811078276, 599325.378924622, 599310.023394395,
599290.690077839, 599271.914703978, 599252.532906822, 599229.797215977,
599202.097394155, 5763610.48439324, 5763616.7157656, 5763621.27416296,
5763624.43500734, 5763633.40050881, 5763639.38340642, 5763645.89049208,
5763653.4729713, 5763659.37588095, 5763666.60960097, 5763676.88897741
), dim = c(11L, 2L), class = c("XY", "LINESTRING", "sfg")),
structure(c(599153.617861475, 599146.140179938, 599135.468484187,
599123.38553011, 599112.149996558, 599090.341255877, 599071.816141346,
599049.86653477, 599041.201483651, 599022.964061505, 598980.441861548,
598941.588973157, 598919.370224986, 598897.926361804, 598885.228478353,
598871.067613897, 598859.525982862, 598849.894242691, 598839.611642872,
598822.882502728, 598804.930836576, 598784.897051154, 598768.484115503,
598766.328345305, 5763689.47173725, 5763690.27503453, 5763689.7135454,
5763688.17320693, 5763687.08021086, 5763686.89528389, 5763684.95513276,
5763683.21890848, 5763683.29902017, 5763684.50905542, 5763682.79160655,
5763681.49667385, 5763680.35723431, 5763684.29905714, 5763685.58823485,
5763686.09333662, 5763686.68206958, 5763686.66585263, 5763685.57204623,
5763678.77303556, 5763666.73451416, 5763652.53771155, 5763641.20759758,
5763639.99848025), dim = c(24L, 2L), class = c("XY", "LINESTRING",
"sfg")), structure(c(599227.531845866, 599202.859751073,
599179.521265781, 599155.284117019, 599129.715033211, 599107.414246027,
599092.184531882, 5764647.31843057, 5764734.50086842, 5764816.29444422,
5764899.29136926, 5764987.67428473, 5765065.81724858, 5765121.03303979
), dim = c(7L, 2L), class = c("XY", "LINESTRING", "sfg")),
structure(c(600594.087149005, 600588.916469261, 5764258.86810428,
5764248.29906133), dim = c(2L, 2L), class = c("XY", "LINESTRING",
"sfg")), structure(c(600579.203159313, 600595.259237174,
5764230.32853955, 5764201.37738517), dim = c(2L, 2L), class = c("XY",
"LINESTRING", "sfg")), structure(c(599238.932778222, 599290.882703812,
5764369.81007426, 5764379.22078406), dim = c(2L, 2L), class = c("XY",
"LINESTRING", "sfg")), structure(c(599687.588911078, 599711.323481742,
5763699.23995036, 5763709.54091522), dim = c(2L, 2L), class = c("XY",
"LINESTRING", "sfg"))), class = c("sfc_LINESTRING", "sfc"
), precision = 0, bbox = structure(c(xmin = 598766.328345305,
ymin = 5763610.48439324, xmax = 600595.259237174, ymax = 5765121.03303979
), class = "bbox"), crs = structure(list(input = "ETRS89 / UTM zone 32N",
wkt = "PROJCRS[\"ETRS89 / UTM zone 32N\",\n BASEGEOGCRS[\"ETRS89\",\n ENSEMBLE[\"European Terrestrial Reference System 1989 ensemble\",\n MEMBER[\"European Terrestrial Reference Frame 1989\"],\n MEMBER[\"European Terrestrial Reference Frame 1990\"],\n MEMBER[\"European Terrestrial Reference Frame 1991\"],\n MEMBER[\"European Terrestrial Reference Frame 1992\"],\n MEMBER[\"European Terrestrial Reference Frame 1993\"],\n MEMBER[\"European Terrestrial Reference Frame 1994\"],\n MEMBER[\"European Terrestrial Reference Frame 1996\"],\n MEMBER[\"European Terrestrial Reference Frame 1997\"],\n MEMBER[\"European Terrestrial Reference Frame 2000\"],\n MEMBER[\"European Terrestrial Reference Frame 2005\"],\n MEMBER[\"European Terrestrial Reference Frame 2014\"],\n ELLIPSOID[\"GRS 1980\",6378137,298.257222101,\n LENGTHUNIT[\"metre\",1]],\n ENSEMBLEACCURACY[0.1]],\n PRIMEM[\"Greenwich\",0,\n ANGLEUNIT[\"degree\",0.0174532925199433]],\n ID[\"EPSG\",4258]],\n CONVERSION[\"UTM zone 32N\",\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\",9,\n ANGLEUNIT[\"degree\",0.0174532925199433],\n ID[\"EPSG\",8802]],\n PARAMETER[\"Scale factor at natural origin\",0.9996,\n SCALEUNIT[\"unity\",1],\n ID[\"EPSG\",8805]],\n PARAMETER[\"False easting\",500000,\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[\"(E)\",east,\n ORDER[1],\n LENGTHUNIT[\"metre\",1]],\n AXIS[\"(N)\",north,\n ORDER[2],\n LENGTHUNIT[\"metre\",1]],\n USAGE[\n SCOPE[\"Engineering survey, topographic mapping.\"],\n AREA[\"Europe between 6°E and 12°E: Austria; Belgium; Denmark - onshore and offshore; Germany - onshore and offshore; Norway including - onshore and offshore; Spain - offshore.\"],\n BBOX[38.76,6,84.33,12]],\n ID[\"EPSG\",25832]]"), class = "crs"), n_empty = 0L)), row.names = c(NA,
-10L), sf_column = "geometry", agr = structure(c(id = NA_integer_), levels = c("constant",
"aggregate", "identity"), class = "factor"), class = c("sf",
"tbl_df", "tbl", "data.frame")) "tbl_df", "tbl", "data.frame"))
1条答案
按热度按时间kgsdhlau1#
虽然通过
rowwise()处理这个问题似乎可以工作，但不确定“正确性”或性能。中断管道只是为了收集一个数据集进行可视化;最后的线在灰色背景上。输入数据：
创建于2023年2月21日，使用reprex v2.0.2