在RI中，要合并两个日期范围内的数据框，取第二个数据框中的所有行，它们都位于第一个数据框的两列日期之间和之间。我找不到严格的R函数或合并函数的版本可以做到这一点，但是我知道sql中有一个“介于”函数，并且我正在考虑尝试sqldf包（尽管我不太熟悉sql ）。如果有更多的R-ish方法可以做到这一点，那将是更好的选择。预先感谢您的帮助！
df1 <- structure(list(ID = 1:2, PtID = structure(c(1L, 1L), .Label = c("T031", "T040", "T045", "T064", "T074", "T081", "T092", "T094", "T096", "T105", "T107", "T108", "T115", "T118", "T120", "T124", "T125", "T128", "T130", "T132", "T138", "T140", "T142", "T142_R1", "T146", "T158", "T159", "T160", "T164", "T166", "T169", "T171", "T173", "T197", "T208", "T214", "T221"), class = "factor"), StartDateTime = structure(list(sec = c(0, 0), min = c(11L, 35L), hour = c(17L, 17L), mday = c(23L, 23L), mon = c(9L, 9L), year = c(112L, 112L), wday …