r - 根据另一个数据表中两个字段的值范围为一个数据表中的字段分配值

Question

我有两个数据表如下:

dt1 <- data.table(range_col = c(1, 7, 10, 15, 20), new_col = NA)
dt2 <- data.table(min_val = c(0, 6, 11, 16), max_val = c(5, 10, 15, 20), value_col = c(100, 200, 300, 400))

现在，根据数据表“dt2”中“range_col”列的值以及“min_val”和“max_val”字段中的值之间的范围，必须将“dt2”的“value_col”中的相应值分配给“new_col” “dt1”的

Answer 1

您可以使用findInterval:

dt1[, new_col := dt2$value_col[findInterval(range_col, dt2$min_val)]]

#    range_col value_col
# 1:         1       100
# 2:         7       200
# 3:        10       200
# 4:        15       300
# 5:        20       400

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另一个(更安全)data.table选项是foverlaps:

setkey(dt2, min_val, max_val)
dt1[, range_col2 := range_col]

foverlaps(dt1, dt2, by.x = c("range_col", "range_col2"))[, c("range_col", "value_col")]

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在dplyr中:

library(dplyr)
inner_join(dt1, dt2, by = join_by(between(range_col, min_val, max_val))) %>% 
  select(range_col, value_col)