7 class ‘SpatialPointsDataFrame’
library("adehabitatHR")SpatialPointsDataFrame是一个s4 class，用于放带了位置坐标的点点集
data(puechabonsp)
relocs <- puechabonsp$relocs
str(relocs)## Formal class 'SpatialPointsDataFrame' [package "sp"] with 5 slots
## ..@ data :'data.frame': 119 obs. of 4 variables:
## .. ..$ Name: Factor w/ 4 levels "Brock","Calou",..: 1 1 1 1 1 1 1 1 1 1 ...
## .. ..$ Age : int [1:119] 2 2 2 2 2 2 2 2 2 2 ...
## .. ..$ Sex : int [1:119] 1 1 1 1 1 1 1 1 1 1 ...
## .. ..$ Date: int [1:119] 930701 930703 930706 930707 930708 930709 930713 930714 930715 930720 ...
## ..@ coords.nrs : num(0)
## ..@ coords : num [1:119, 1:2] 699889 700046 698840 699809 698627 ...
## .. ..- attr(*, "dimnames")=List of 2
## .. .. ..$ : NULL
## .. .. ..$ : chr [1:2] "X" "Y"
## ..@ bbox : num [1:2, 1:2] 698626 3157848 701410 3161678
## .. ..- 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 NA对比它和自己建的s4 class的结构，差不多的。
setClass("student", slots = list(name = "character", age = "numeric", GPA = "numeric",
data = "data.frame"))
table <- data.frame(name = c("Jack", "Mary"), id = c("001", "002"), salary = c(1000,
2000))
s4 <- new("student", name = "John", age = 21, GPA = 3.5, data = table)
str(s4)## Formal class 'student' [package ".GlobalEnv"] with 4 slots
## ..@ name: chr "John"
## ..@ age : num 21
## ..@ GPA : num 3.5
## ..@ data:'data.frame': 2 obs. of 3 variables:
## .. ..$ name : chr [1:2] "Jack" "Mary"
## .. ..$ id : chr [1:2] "001" "002"
## .. ..$ salary: num [1:2] 1000 2000也可以像一般的s4 class一样用@访问元素
head(s4@data)## name id salary
## 1 Jack 001 1000
## 2 Mary 002 2000head(relocs@data)## Name Age Sex Date
## 1 Brock 2 1 930701
## 2 Brock 2 1 930703
## 3 Brock 2 1 930706
## 4 Brock 2 1 930707
## 5 Brock 2 1 930708
## 6 Brock 2 1 930709不同的是SpatialPointsDataFrame对象支持类似数据框的访问方式。用$访问普通s4 class会出错:
s4$a1## Error in s4$a1: $ operator not defined for this S4 class但是可以SpatialPointsDataFrame不会
relocs$Name## [1] Brock Brock Brock Brock Brock Brock Brock Brock Brock Brock
## [11] Brock Brock Brock Brock Brock Brock Brock Brock Brock Brock
## [21] Brock Brock Brock Brock Brock Brock Brock Brock Brock Brock
## [31] Calou Calou Calou Calou Calou Calou Calou Calou Calou Calou
## [41] Calou Calou Calou Calou Calou Calou Calou Calou Calou Chou
## [51] Chou Chou Chou Chou Chou Chou Chou Chou Chou Chou
## [61] Chou Chou Chou Chou Chou Chou Chou Chou Chou Chou
## [71] Chou Chou Chou Chou Chou Chou Chou Chou Chou Chou
## [81] Chou Chou Chou Chou Chou Chou Chou Chou Chou Jean
## [91] Jean Jean Jean Jean Jean Jean Jean Jean Jean Jean
## [101] Jean Jean Jean Jean Jean Jean Jean Jean Jean Jean
## [111] Jean Jean Jean Jean Jean Jean Jean Jean Jean
## Levels: Brock Calou Chou Jean还有这样
head(relocs[[1]])## [1] Brock Brock Brock Brock Brock Brock
## Levels: Brock Calou Chou Jeanhead(s4[[1]]) # 这个不行## Error in s4[[1]]: this S4 class is not subsettable其他的
head(relocs[[1, ]]) # 跟head(relocs[[1]])一样## [1] Brock Brock Brock Brock Brock Brock
## Levels: Brock Calou Chou Jeanrelocs[[1]][1]## [1] Brock
## Levels: Brock Calou Chou Jeanhead(relocs[1]) # 这个返回结果仍然是SpatialPointsDataFrame，但只带第一列的数据## coordinates Name
## 1 (699889, 3161560) Brock
## 2 (700046, 3161540) Brock
## 3 (698840, 3161030) Brock
## 4 (699809, 3161500) Brock
## 5 (698627, 3160940) Brock
## 6 (698719, 3160990) Brock
## Coordinate Reference System (CRS) arguments: NAs4[1] # 普通s4 class同样不支持## Error in s4[1]: object of type 'S4' is not subsettable还有
head(relocs[, 1]) # 跟relocs[1]一样## coordinates Name
## 1 (699889, 3161560) Brock
## 2 (700046, 3161540) Brock
## 3 (698840, 3161030) Brock
## 4 (699809, 3161500) Brock
## 5 (698627, 3160940) Brock
## 6 (698719, 3160990) Brock
## Coordinate Reference System (CRS) arguments: NArelocs[1, ] # 第一个点## coordinates Name Age Sex Date
## 1 (699889, 3161559) Brock 2 1 930701跟数据框不同的是：这样不行
relocs[[, 1]]## Error in relocs[[, 1]]: incorrect number of subscriptsrelocs[[1, 1]]## Error in relocs[[1, 1]]: incorrect number of subscripts# 只能这样
relocs[[1]][1]## [1] Brock
## Levels: Brock Calou Chou Jean推荐的做法是把SpatialPointsDataFrame转换成数据框，这样就啥都行了。
relocs <- as.data.frame(relocs)
relocs[1, 1]## [1] Brock
## Levels: Brock Calou Chou Jeanhead(relocs[, 1])## [1] Brock Brock Brock Brock Brock Brock
## Levels: Brock Calou Chou Jean普通的s4对象不能转换成数据框
as.data.frame(s4)## Error in as.data.frame.default(s4): cannot coerce class 'structure("student", package = ".GlobalEnv")' to a data.frame