问题描述
我有两个具有相同结构的data.table。两个关键列,后跟多个数据列。数据列的数量可能会有所不同。
我想将第二个data.table中的值添加到第一个data.table中的相应行/列中。
I have two data.table with the same structure. Two key columns followed by a number of data columns. The number of data columns may vary.I want to add the values from the second data.table to the corresponding rows/columns in the first data.table.
DT1 <- cbind(data.table(loc=c("L1","L2","L3"), product=c("P1","P2","P1")), matrix(10,nrow=3,ncol=12))
setkey(DT1, loc, product)
DT1
loc product V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12
1: L1 P1 10 10 10 10 10 10 10 10 10 10 10 10
2: L2 P2 10 10 10 10 10 10 10 10 10 10 10 10
3: L3 P1 10 10 10 10 10 10 10 10 10 10 10 10
DT2 <- cbind(data.table(loc=c("L2","L3"), product=c("P2","P1")), matrix(1:24,nrow=2,ncol=12))
setkey(DT2, loc, product)
loc product V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12
1: L2 P2 1 3 5 7 9 11 13 15 17 19 21 23
2: L3 P1 2 4 6 8 10 12 14 16 18 20 22 24
到目前为止,我最好的选择是
My best bet so far is the following
DT1[DT2, 3:14 := as.data.table(DT1[DT2, 3:14, with=FALSE] + DT2[, 3:14, with=FALSE]), with=FALSE]
loc product V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12
1: L1 P1 10 10 10 10 10 10 10 10 10 10 10 10
2: L2 P2 11 13 15 17 19 21 23 25 27 29 31 33
3: L3 P1 12 14 16 18 20 22 24 26 28 30 32 34
请注意,nrow和ncol以及loc和product条目都是可变的,具体取决于源数据。
Note that nrow and ncol and the loc and product entries are all variable depending on the source data.
如果DT2中的每一行都与DT1中的每一行匹配,则此方法有效,否则将产生意外结果。
是否有更严格/优雅的方法来表示RHS来完成同时引用DT1和DT2的可变数量的列分配?
This works if every row in DT2 matches one in DT1, but otherwise will have unexpected results.Is there a more rigorous/elegant way to express the RHS to do this variable number of column assignments referring to both DT1 and DT2?
推荐答案
怎么样:
cols = paste0('V', 1:12)
DT1[DT2, (cols) := setDT(mget(cols)) + mget(paste0('i.', cols))]
DT1
# loc product V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12
#1: L1 P1 10 10 10 10 10 10 10 10 10 10 10 10
#2: L2 P2 11 13 15 17 19 21 23 25 27 29 31 33
#3: L3 P1 12 14 16 18 20 22 24 26 28 30 32 34
这篇关于r data.table更新联接中的多个列的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!