R中的Complexe非等合并

我正在尝试在两个表之间进行复杂的非相等联接。上一次useR2016（）中的一次演示激发了我的灵感，使我相信这将是data.table的合适任务。我的表1看起来像：

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

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

我试过这样的方法：

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

---

dt1[dt2，on=。（sp=sp，dbh>=dbh_min，dbh所以我非常接近。我有两个问题，首先是data.table包（）的错误安装导致了一个模糊的错误

在解决了这个问题后，我走近一点，发现：

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

dt1[dt2，on=（sp=sp，dbh>=dbh_min，dbh对于像这样的“中间”连接，也可以使用
数据。table:：foverlaps
，它连接两个
数据。table
在重叠的范围上，而不是使用非相等连接

以相同的示例为例，下面的代码将生成所需的结果

# foverlap tests the overlap of two ranges.  Create a second column,
# dbh2, as the end point of the range.
dt1[, dbh2 := dbh]

# foverlap requires the second argument to be keyed
setkey(dt1, sp, dbh, dbh2)

# find rows where dbh falls between dbh_min and dbh_max, and drop unnecessary
# columns afterwards
foverlaps(dt2, dt1, by.x = c("sp", "dbh_min", "dbh_max"), by.y = key(dt1),
          nomatch = 0)[
  ,
  -c("dbh2", "dbh_min", "dbh_max")
]

#  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

使用第一种方法，您可以使用
x.*
和
i.*
前缀来枚举所需的列：
dt1[dt2，on=。（sp，dbh>=dbh_min，dbh请遵循@Frank关于使用
x.
前缀的建议。这对于非等联接特别有用，因为与基数R一致，您在联接中使用了重命名列。这在中进行了讨论。感谢@Frank，您的评论让我更接近完美！将
nomatch=0
添加到您的调用中使其变得完美！这里有一种非等连接的方法来做同样的事情。
dt1[dt2，on=“sp”，allow.cartesian=T][dbh>=dbh\u min&dbht这是一个很好的非等联接线程，尽管有点旧。@ironv如果两个DTs之间没有一个公共列，如何避免使用非等联接。在本例中，有一个公共列
sp
。这是有意义的。
dt2[dt1, on=.(sp=sp, dbh_min<=dbh, dbh_max>=dbh)]

# foverlap tests the overlap of two ranges.  Create a second column,
# dbh2, as the end point of the range.
dt1[, dbh2 := dbh]

# foverlap requires the second argument to be keyed
setkey(dt1, sp, dbh, dbh2)

# find rows where dbh falls between dbh_min and dbh_max, and drop unnecessary
# columns afterwards
foverlaps(dt2, dt1, by.x = c("sp", "dbh_min", "dbh_max"), by.y = key(dt1),
          nomatch = 0)[
  ,
  -c("dbh2", "dbh_min", "dbh_max")
]

#  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