r语言 - 按级别拆分空间线数据帧轮廓

Question

我有一个包含三个轮廓 0.2、0.5 和 0.95 的空间线数据帧，并希望能够选择一个级别进行进一步计算（例如 over、gIntersect 等）。

我尝试使用data@data$level[[1]]选择第一级，但这不起作用

class       : SpatialLinesDataFrame 
features    : 3 
extent      : 11.44765, 11.51037, 62.11384, 62.13572  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +towgs84=0,0,0 
variables   : 1
names       : level 
min values  :   0.2 
max values  :  0.95 
Formal class 'SpatialLinesDataFrame' [package "sp"] with 4 slots
  ..@ data       :'data.frame': 3 obs. of  1 variable:
  .. ..$ level: Factor w/ 3 levels "0.2","0.5","0.95": 1 2 3
  ..@ lines      :List of 3
  .. ..$ :Formal class 'Lines' [package "sp"] with 2 slots
  .. .. .. ..@ Lines:List of 6
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:9, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:7, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:11, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:7, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:25, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:21, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. ..@ ID   : chr "C_1"
  .. ..$ :Formal class 'Lines' [package "sp"] with 2 slots
  .. .. .. ..@ Lines:List of 10
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:31, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:51, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:13, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:55, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:19, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:25, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:11, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:31, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:11, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:37, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. ..@ ID   : chr "C_2"
  .. ..$ :Formal class 'Lines' [package "sp"] with 2 slots
  .. .. .. ..@ Lines:List of 2
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:173, 1:2] 11.4 11.4 11.4 11.4 11.4 ...
  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
  .. .. .. .. .. .. ..@ coords: num [1:693, 1:2] 11.5 11.5 11.5 11.5 11.5 ...
  .. .. .. ..@ ID   : chr "C_3"
  ..@ bbox       : num [1:2, 1:2] 11.4 62.1 11.5 62.1
  .. ..- attr(*, "dimnames")=List of 2
  .. .. ..$ : chr [1:2] "x" "y"
  .. .. ..$ : chr [1:2] "min" "max"
  ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slot
  .. .. ..@ projargs: chr "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs +towgs84=0,0,0"

Answer 1

split(data, data@data$level)

伎俩:)