要从SpatialPolygonsDataFrame中删除特定的多边形/空间特征，请使用以下代码。这行得通，但是尽管如此，我还是想找到一种更优雅的方式来做，也许您有任何建议如何一步一步完成工作……在此先谢谢了！
我已经对这个问题进行了调查，但是还没有找到令人满意的解决方案。 查看网址：Remove certain polygons from SpatialPolygonsDataFrame
data_ftprints
class : SpatialPolygonsDataFrame
features : 25
extent : ?????.??, ??????.?, ???????, ??????? (xmin, xmax, ymin, ymax)
crs : +init=epsg:32638 +proj=utm +zone=38 +datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0
variables : 1
names : temp_id
min values : 1
max values : 25
# this is my SpatialPolygonsDataFrame with 25features, each with a unique id (temp_id).
# please apologize that i disguised my studyarea (extent).
data_ftprints <- data_ftprints[data_ftprints@data$temp_id != 15, ]
data_ftprints <- data_ftprints[data_ftprints@data$temp_id != 21, ]
# delete polygons/ spatial features which do not belong to the study area
# THIS IS WORKING BUT NOT ELEGANT; I WANT TO DO IT IN ONE STEP