物种分布建模中x@presence空对象错误求解（R语言sdm包）

环境信息 #

• R版本：4.4.1
• 使用工具：Naimi于2016年开发的sdm包

报错场景 #

运行以下建模代码时触发错误：

model <- sdm(Species ~ ., data = sdm_data, 
    methods = c('glm', 'gam', 'gbm', 'rf', 'svm', 'mars'))

错误信息：

Error in x@presence : no applicable method for @ applied to an object of class "NULL"

完整相关代码 #

bioclim_files <- list.files(pattern = "*.tif$", full.names = TRUE)
Study_Area <- st_read("shp/3Province.shp")
DEM <- rast ("shp/DEM.tif")          
DEM_crop <- crop (DEM, Study_Area)
DEM_mask <- mask (DEM_crop, Study_Area) 
Bio <- rast(bioclim_files)
Bio <- crop (Bio, Study_Area)
Bio <- mask (Bio, Study_Area)
ext(Bio)
ext(DEM)
Bio_crop <- crop(Bio, ext(DEM))
Bio_resample <- resample(Bio_crop, DEM) #Bio1_2_4_8_15_18
occurance_data <- import("p_i.xlsx")
sdm_data <- sdmData(Species ~ . + coords(Lon + Lat), 
                    train = occurance_data, 
                    predictors = Bio_resample)
print(sdm_data)
summary(sdm_data)
model <- sdm(Species ~ ., data = sdm_data,
             methods = c('glm', 'gam', 'gbm', 'rf', 'svm', 'mars'))
str(sdm_data)

物种出现数据（occurance_data）详情 #

> names(occurance_data)
[1] "OBJECTID" "Species"  "Lon"      "Lat"

> str(occurance_data)

'data.frame':   78 obs. of  4 variables:
 $ OBJECTID: num  1 2 3 4 5 6 7 8 9 10 ...
 $ Species : chr  "p_i" "p_i" "p_i" "p_i" ...
 $ Lon     : num  50.8 50.8 50.9 51.3 51.3 ...
 $ Lat     : num  36.7 36.7 36.7 36.4 36.7 ...

> summary(occurance_data)
    OBJECTID       Species               Lon             Lat       
 Min.   : 1.00   Length:78          Min.   :49.01   Min.   :36.12  
 1st Qu.:20.25   Class :character   1st Qu.:50.86   1st Qu.:36.29  
 Median :39.50   Mode  :character   Median :52.36   Median :36.42  
 Mean   :39.50                      Mean   :51.97   Mean   :36.56  
 3rd Qu.:58.75                      3rd Qu.:53.09   3rd Qu.:36.76  
 Max.   :78.00                      Max.   :55.59   Max.   :37.39 

已尝试的无效方案 #

• 调整变量名大小写（如Species/species）
• 增加物种出现数据量

求可行的解决方法。

内容的提问来源于stack exchange，提问作者Simon