r - 在向量中查找以前的相同值并应用某些条件

Question

对于 myvector1 的每个值我想知道mycategory myvector1 中前一个相同值的值，鉴于 mystatus为 ON，否则我会寻找相应的下一个相同值，直到它为 ON。

说明如下所示:

对于“myvector”的给定位置，给我他的值(value)。

寻找中间前一个相同值的位置
“我的向量”

检查关联状态。如果是 ON 给我他的关联
“我的类别”。如果为 OFF，则重复转到第 2 点。

将获得的“mycategory”分配给新向量“mysolution”。

给定数据集 mydf我要找的是DesiredSolution (我手动填写)。

mydf <- structure(list(myvector1 = structure(c(1L, 2L, 3L, 4L, 5L, 1L, 
2L, 4L, 5L, 2L, 3L, 4L, 5L, 2L, 3L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 
2L, 4L, 5L, 1L, 1L, 2L, 3L, 4L, 5L, 3L), .Label = c("0", "1", 
"2", "3", "4"), class = "factor"), mystatus = structure(c(2L, 
1L, 2L, 2L, 1L, 2L, 2L, 2L, 2L, 1L, 2L, 2L, 2L, 1L, 2L, 2L, 2L, 
1L, 2L, 2L, 1L, 1L, 2L, 1L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 2L), .Label = c("OFF", 
"ON"), class = "factor"), mycategory = structure(c(2L, 2L, 3L, 
1L, 1L, 1L, 1L, 3L, 3L, 1L, 2L, 2L, 3L, 1L, 1L, 1L, 1L, 1L, 2L, 
2L, 3L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 3L, 3L), .Label = c("bye", 
"hi", "stay"), class = "factor"), DesiredSolution = structure(c(3L, 
3L, 3L, 3L, 3L, 2L, 3L, 1L, 3L, 1L, 4L, 4L, 4L, 1L, 2L, 4L, 1L, 
1L, 1L, 2L, 1L, 1L, 1L, 2L, 1L, 1L, 1L, 1L, 2L, 2L, 1L, 2L), .Label = c("bye", 
"hi", "NA", "stay"), class = "factor")), .Names = c("myvector1", 
"mystatus", "mycategory", "DesiredSolution"), row.names = c(NA, 
-32L), class = "data.frame")

Answer 1

用数据表...

library(data.table)
setDT(mydf)
mydf[, r := .I]
mydf[, v := mydf[mystatus == "ON"][mydf, on=.(r < r, myvector1), mult="last", x.mycategory]]

这使

    myvector1 mystatus mycategory DesiredSolution  r    v
 1:         0       ON         hi              NA  1   NA
 2:         1      OFF         hi              NA  2   NA
 3:         2       ON       stay              NA  3   NA
 4:         3       ON        bye              NA  4   NA
 5:         4      OFF        bye              NA  5   NA
 6:         0       ON        bye              hi  6   hi
 7:         1       ON        bye              NA  7   NA
 8:         3       ON       stay             bye  8  bye
 9:         4       ON       stay              NA  9   NA
10:         1      OFF        bye             bye 10  bye
11:         2       ON         hi            stay 11 stay
12:         3       ON         hi            stay 12 stay
13:         4       ON       stay            stay 13 stay
14:         1      OFF        bye             bye 14  bye
15:         2       ON        bye              hi 15   hi
16:         4       ON        bye            stay 16 stay
17:         0       ON        bye             bye 17  bye
18:         1      OFF        bye             bye 18  bye
19:         2       ON         hi             bye 19  bye
20:         3       ON         hi              hi 20   hi
21:         4      OFF       stay             bye 21  bye
22:         0      OFF        bye             bye 22  bye
23:         1       ON        bye             bye 23  bye
24:         3      OFF        bye              hi 24   hi
25:         4       ON        bye             bye 25  bye
26:         0      OFF        bye             bye 26  bye
27:         0      OFF         hi             bye 27  bye
28:         1      OFF         hi             bye 28  bye
29:         2      OFF         hi              hi 29   hi
30:         3      OFF         hi              hi 30   hi
31:         4      OFF       stay             bye 31  bye
32:         2       ON       stay              hi 32   hi
    myvector1 mystatus mycategory DesiredSolution  r    v

工作原理:在 mydf[mystatus == "ON"] 中查找行其中行号r较低和myvector1火柴。返回 mycategory , 如果有多个匹配项，则取最后一个匹配行。