r - R 中复杂的非等值合并

Question

我正在尝试在两个表之间进行复杂的非等值连接。我受到了上次 useR2016 ( https://channel9.msdn.com/events/useR-international-R-User-conference/useR2016/Efficient-in-memory-non-equi-joins-using-datatable ) 中的演示的启发，这让我相信这将是 data.table 的合适任务。我的表 1 如下所示:

library(data.table)
sp <- c("SAB","SAB","SAB","SAB","EPN","EPN","BOP","BOP","BOP","BOP","BOP","PET","PET","PET")
dbh <- c(10,12,16,22,12,16,10,12,14,20,26,12,16,18)
dt1 <- data.table(sp,dbh)
dt1
     sp dbh
 1: SAB  10
 2: SAB  12
 3: SAB  16
 4: SAB  22
 5: EPN  12
 6: EPN  16
 7: BOP  10
 8: BOP  12
 9: BOP  14
10: BOP  20
11: BOP  26
12: PET  12
13: PET  16
14: PET  18

这是树木及其胸径的列表。我的第二个表(如下)给出了一个通用表，其中为每个树种提供了一个胸径范围，以对树的大小类别进行分类:

gr_sp <- c("RES","RES","RES","RES","RES","RES", "DEC", "DEC", "DEC", "DEC", "DEC", "DEC")
sp <- c("SAB","SAB", "SAB", "EPN", "EPN", "EPN", "BOP", "BOP", "BOP", "PET", "PET", "PET")
dbh_min <- c(10, 16, 22, 10, 14, 20, 10, 18, 24, 10, 20, 26)
dbh_max <- c(14, 20, 30, 12, 18, 30, 16, 22, 30, 18, 24, 30)
dhb_clas <- c("s", "m", "l", "s", "m", "l", "s", "m", "l", "s", "m", "l")

dt2 <- data.table(gr_sp, sp, dbh_min, dbh_max, dhb_clas)
dt2
    gr_sp  sp dbh_min dbh_max dhb_clas
 1:   RES SAB      10      14        s
 2:   RES SAB      16      20        m
 3:   RES SAB      22      30        l
 4:   RES EPN      10      12        s
 5:   RES EPN      14      18        m
 6:   RES EPN      20      30        l
 7:   DEC BOP      10      16        s
 8:   DEC BOP      18      22        m
 9:   DEC BOP      24      30        l
10:   DEC PET      10      18        s
11:   DEC PET      20      24        m
12:   DEC PET      26      30        l

我希望我的最终表是按物种(“sp”字段)连接的两个表，并且在“DBH_MIN”和“DBH_MAX”规定的 dhb 范围内。这将使我的表格看起来像:

data.table(dt1, gr_sp = c("RES","RES","RES","RES","RES","RES","DEC","DEC","DEC","DEC","DEC","DEC","DEC","DEC"), dhb_clas = c("s","s","m","l","s","m","s","s","s","m","l","s","s","s"))
     sp dbh gr_sp dhb_clas
 1: SAB  10   RES        s
 2: SAB  12   RES        s
 3: SAB  16   RES        m
 4: SAB  22   RES        l
 5: EPN  12   RES        s
 6: EPN  16   RES        m
 7: BOP  10   DEC        s
 8: BOP  12   DEC        s
 9: BOP  14   DEC        s
10: BOP  20   DEC        m
11: BOP  26   DEC        l
12: PET  12   DEC        s
13: PET  16   DEC        s
14: PET  18   DEC        s

我尝试过类似的方法:

dt1[dt2, on=.(sp=sp, dbh>=dbh_min, dbh<=dbh_max)]

这给出了太多行...

感谢您的帮助

Answer 1

所以我非常接近。我遇到了 2 个问题，首先是 data.table 包 ( Data table error could not find function "." ) 的错误安装导致了一个模糊的错误。

解决这个问题后，我更仔细地发现:

dt1[dt2, on=.(sp=sp, dbh>=dbh_min, dbh<=dbh_max), nomatch=0]

用一个糟糕的 dbh 列给了我我想要的东西。反转命令:

dt2[dt1, on=.(sp=sp, dbh_min<=dbh, dbh_max>=dbh)]

仅用一个无用的额外列解决了问题。