レベル別にSpatialLinesDataFrame輪郭を分割する

Question

私は3つの輪郭0.2,0.5、および0.95を含むSpatialLinesDataFrameを持っており、さらに計算するために1つのレベルを選択できるようにしたいと考えています（例：over、gIntersectなど）。

私は最初のレベルの選択のためのdata@data$level[[1]]を使用して試してみましたが、それは

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) 

はトリックをした動作しません:)