我有一个 data.table，其中包含多个站点超过 15 天的温度和其他天气信息的观测值。这dput是针对两个站点的所有观察结果。
library(data.table)
structure(list(site = c("100", "100", "100", "100", "100", "100",
"100", "100", "100", "100", "100", "100", "100", "100", "100"
), precursor_date = structure(c(15203, 15202, 15201, 15200, 15199,
15198, 15197, 15196, 15195, 15194, 15193, 15192, 15191, 15190,
15189), class = "Date"), lat = c(46.864, 46.864, 46.864, 46.864,
46.864, 46.864, 46.864, 46.864, 46.864, 46.864, 46.864, 46.864,
46.864, 46.864, 46.864), lon = c(-67.998, -67.998, -67.998, -67.998,
-67.998, -67.998, -67.998, -67.998, -67.998, -67.998, -67.998,
-67.998, -67.998, -67.998, -67.998), origDate …