在 r 中返回具有匹配条件的值 [英] Return values with matching conditions in r

问题描述

我想根据切分标准在另一列中返回具有匹配条件的值.如果变量中的切分分数不可用，我想获取最接近的较大值.这是数据集的快照:

I would like to return values with matching conditions in another column based on a cut score criterion. If the cut scores are not available in the variable, I would like to grab closest larger value. Here is a snapshot of dataset:

ids <- c(1,2,3,4,5,6,7,8,9,10)
scores.a <- c(512,531,541,555,562,565,570,572,573,588)
scores.b <- c(12,13,14,15,16,17,18,19,20,21)
data <- data.frame(ids, scores.a, scores.b)
> data
   ids scores.a scores.b
1    1      512       12
2    2      531       13
3    3      541       14
4    4      555       15
5    5      562       16
6    6      565       17
7    7      570       18
8    8      572       19
9    9      573       20
10  10      588       21

cuts <- c(531, 560, 571)

我想获取与第一个cut score对应的score.b值，即13.然后，抓取第二个cut(560)分数对应的score.b值，但它不在score.a中，所以我想得到score.a值562(最接近 560)，对应的值为 16.最后，对于第三个切割分数 (571)，我想得到 19，这是与第三个切割分数最接近的值 (572) 的对应值.

I would like to grab score.b value corresponding to the first cut score, which is 13. Then, grab score.b value corresponding to the second cut (560) score but it is not in the score.a, so I would like to get the score.a value 562 (closest to 560), and the corresponding value would be 16. Lastly, for the third cut score (571), I would like to get 19 which is the corresponding value of the closest value (572) to the third cut score.

这是我想要的.

       scores.b
cut.1  13
cut.2  16
cut.3  19

有什么想法吗?谢谢

推荐答案

我们可以使用滚动连接

library(data.table)
setDT(data)[data.table(cuts = cuts), .(ids = ids, cuts, scores.b), 
          on = .(scores.a = cuts), roll = -Inf]
#   ids cuts scores.b
#1:   2  531       13
#2:   5  560       16
#3:   8  571       19

<小时>

或者另一个选项是 findInterval 从 base R 改变符号并取 reverse

---

Or another option is findInterval from base R after changing the sign and taking the reverse

with(data, scores.b[rev(nrow(data) + 1 - findInterval(rev(-cuts), rev(-scores.a)))])
#[1] 13 16 19

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