空间核密度估计，但我收到此错误“错误：[rast] 无法从单个 x 坐标创建栅格几何图形”

Question

library(sf)
library(spatialEco)
library(dplyr)

load("C:/Users/user/Desktop/Movedata/geo_record.RData")

geo_data <- geo_record %>%
  rename(x = coords.x1,
         y = coords.x2)
movement_points <- geo_data[-c(9)]

movement_points$longitude <- movement_points$x
movement_points$latitude <-movement_points$y
movement_points_sf <- st_as_sf(movement_points, coords = c("x", "y"), crs = 4326, 
                  agr = "constant")
pt.kde <- sf.kde(x = movement_points_sf, bw = 5, standardize = TRUE, res=40)

我有一个错误 pt.kde <- sf.kde(x = movement_points_sf, bw = 5, standardize = TRUE, res=40)

计算未加权的kde

错误：[rast] 无法从单个 x 坐标创建栅格几何图形 我正在使用 RStudio

Answer 1

您收到的错误可能是因为您的数据是由地理坐标系（4326）定义的，并且

sf.kde()

期望投影数据，例如3857. 这是一个工作流程，其中有一些示例数据可供说明。此示例使用伪墨卡托 (EPSG:3857) 投影坐标系。您需要确保您选择的投影对于您的数据和位置而言是正确的。

请注意，因为您使用的是

dplyr

，所以您可以通过管道传输这些单独的代码行：

library(sf)
library(spatialEco)
library(dplyr)

# Create some example data
set.seed(1)
geo_record <- data.frame(coords.x1 = runif(100, 45.000, 45.002),
                         coords.x2 = runif(100, 45.000, 45.002))

geo_record <- geo_record %>%
  mutate(!!!setNames(rep(NA, length(letters[1:7])), letters[1:7]))

geo_record <- geo_record %>%
  mutate(across(a:g, ~ replace(.x, is.na(.x), 
                            sample(1:10, sum(is.na(.x)), replace = TRUE))))

head(geo_record)
  coords.x1 coords.x2  a  b c  d e f  g
1  45.00053  45.00131 10  2 5  7 6 5  6
2  45.00074  45.00071 10  1 5 10 4 8  5
3  45.00115  45.00054  2  8 3  5 8 3  5
4  45.00182  45.00199  2  5 5  8 2 8  7
5  45.00040  45.00127  3  8 8  5 4 5  9
6  45.00180  45.00043  1 10 7  3 2 3 10

# Modify column names, remove unwanted column, add new columns, convert to sf
movement_points_sf <- geo_record %>%
  rename(x = coords.x1,
         y = coords.x2) %>%
  select(-9) %>%
  mutate(longitude = x,
         latitude = y) %>%
  st_as_sf(., 
           coords = c("x", "y"), 
           crs = 4326, 
           agr = "constant") %>%
  st_transform(3857)

head(movement_points_sf)
# Simple feature collection with 6 features and 8 fields
# Attribute-geometry relationships: constant (8)
# Geometry type: POINT
# Dimension:     XY
# Bounding box:  xmin: 5009422 ymin: 5621589 xmax: 5009579 ymax: 5621834
# Projected CRS: WGS 84 / Pseudo-Mercator
   a  b c  d e f longitude latitude                geometry
1 10  2 5  7 6 5  45.00053 45.00131 POINT (5009436 5621728)
2 10  1 5 10 4 8  45.00074 45.00071 POINT (5009460 5621633)
3  2  8 3  5 8 3  45.00115 45.00054 POINT (5009505 5621607)
4  2  5 5  8 2 8  45.00182 45.00199 POINT (5009579 5621834)
5  3  8 8  5 4 5  45.00040 45.00127 POINT (5009422 5621721)
6  1 10 7  3 2 3  45.00180 45.00043 POINT (5009577 5621589)

# Calculate KDE
pt.kde <- sf.kde(x = movement_points_sf, 
                 bw = 5, 
                 standardize = TRUE, 
                 res = 40)

pt.kde
class       : SpatRaster 
dimensions  : 4, 7, 1  (nrow, ncol, nlyr)
resolution  : 28.57143, 80  (x, y)
extent      : 5009394, 5009594, 5621486, 5621806  (xmin, xmax, ymin, ymax)
coord. ref. : WGS 84 / Pseudo-Mercator (EPSG:3857) 
source(s)   : memory
name        :        z 
min value   :    0.000 
max value   : 3274.323