R数据表setkey - 错误一些列不在data.table中 [英] R Data table setkey - error some columns are not in the data.table

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问题描述

我想使用data.table setkey 与预定义的列表 id categories ,但会收到错误消息:

  setkey(tr_id_cat_dt,id,categories)
在setkeyv(x,cols,verbose = verbose)中出错:
一些列不在data.table中:categories

我想要 id





$ b

$ b

id和类别是值列表,例如:

  categories = c(9115L,9909L,3203L, 5558L,4401L,1703L,1726L,3504L,3509L,
5122L,5616L,5619L,2202L,2119L,6202L,5824L,799L,4517L,
7205L,706L)


dput(head(tr_id_cat_dt))
结构(列表(id = c(86246,86246,86246,86246,86246,86246
),category = c(706L,706L,706L, 706L,706L,706L)),.Names = c(id,
category),sorted = c(id,category),class = c(data.table,
data.frame),row.names = c(NA,-6L),.internal.selfref =< pointer:0x015424a0>)


解决方案

只能在 setkey > data.table (如@Roland已经指出)。

  require(data.table) 
DT = data.table(x = 1:2,y = 3:4)
z = 5:6
setkey(DT,x)#works
setkey z)#does not
#setkeyv中的错误(x,cols,verbose = verbose,physical = physical):
#有些列不在data.table中:z

setkey(DT [,z:= z],z)#works

HTH


I would like to use data.table setkey with pre-defined lists id and categories, but get an error message:

> setkey(tr_id_cat_dt, id, categories)
Error in setkeyv(x, cols, verbose = verbose) : 
  some columns are not in the data.table: categories

I would like all the elements of id and categories to appear as keys.

Is this possible?


id and categorie are lists of values, for example:

categories = c(9115L, 9909L, 3203L, 5558L, 4401L, 1703L, 1726L, 3504L, 3509L, 
5122L, 5616L, 5619L, 2202L, 2119L, 6202L, 5824L, 799L, 4517L, 
7205L, 706L)


dput(head(tr_id_cat_dt))
structure(list(id = c(86246, 86246, 86246, 86246, 86246, 86246
    ), category = c(706L, 706L, 706L, 706L, 706L, 706L)), .Names = c("id", 
    "category"), sorted = c("id", "category"), class = c("data.table", 
    "data.frame"), row.names = c(NA, -6L), .internal.selfref = <pointer: 0x015424a0>)

解决方案

You can setkey only on the columns of a data.table (as @Roland already pointed out).

require(data.table)
DT = data.table(x = 1:2, y=3:4)
z = 5:6
setkey(DT, x) # works
setkey(DT, z) # doesn't
# Error in setkeyv(x, cols, verbose = verbose, physical = physical) : 
#   some columns are not in the data.table: z

setkey(DT[, z := z], z) # works

HTH

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