Question

我想创建一个索引列，该索引列会查找诸如“开始”和“结束”之类的某些关键字以分配唯一的ID，并具有一个计数器/循环以在映射下一个“开始”时分配序列中的下一个数字< / p>

library(data.table)
in.data <- data.table(colA=c("random", "random", "random", "random", "random", "start", "random", "random", "end", "start", "random", "end", "start", "end", "random"))
in.data$wanted.column <- c(NA, NA, NA, NA, NA, 1, 1, 1, 1, 2, 2, 2, 3, 3, NA)

           in.data
              colA wanted.column
         1: random            NA
         2: random            NA
         3: random            NA
         4: random            NA
         5: random            NA
         6:  start             1
         7: random             1
         8: random             1
         9:    end             1
        10:  start             2
        11: random             2
        12:    end             2
        13:  start             3
        14:    end             3
        15: random            NA

Answer 1

数据：

in.data <- data.table(colA=c("random", "random", "random", "random", "random", "start", "random", "random", "end", "start", "random", "end", "start", "end", "random"))
in.data$wanted.column <- c(NA, NA, NA, NA, NA, 1, 1, 1, 1, 2, 2, 2, 3, 3, NA)

代码：

in.data$wanted.column2 = NA
IND <- min(which(in.data$colA %in% "start")):max(which(in.data$colA %in% "end"))
in.data$wanted.column2[IND] = cumsum(in.data$colA %in% "start")[IND]

结果：

#      colA wanted.column wanted.column2
# 1: random            NA             NA
# 2: random            NA             NA
# 3: random            NA             NA
# 4: random            NA             NA
# 5: random            NA             NA
# 6:  start             1              1
# 7: random             1              1
# 8: random             1              1
# 9:    end             1              1
#10:  start             2              2
#11: random             2              2
#12:    end             2              2
#13:  start             3              3
#14:    end             3              3
#15: random            NA             NA

用NA预先填充一列
获取从第一个“开始”到最后一个“结束”的索引
进行分组并将其添加到预期的位置

基于开始和结束值的行的索引块

1 个答案: