r - data.table bug，导致 R 中出现段错误

Question

以下代码在运行 data.table 1.8.9 的 R 2.15.0 中出现段错误。

library(data.table)
d = data.table(date = c(1,2,3,4,5), value = c(1,2,3,4,5))

# works as expected
d[-5][, mean(value), by = list(I(as.integer((date+1)/2)))]

# crashes R
d[-5, mean(value), by = list(I(as.integer((date+1)/2)))]

相关说明中，以下两个命令具有非常不同的输出:

d[-5][, value, by = list(I(as.integer((date+1)/2)))]
#    I value
# 1: 1     1
# 2: 1     2
# 3: 2     3
# 4: 2     4

d[-5, value, by = list(I(as.integer((date+1)/2)))]
#    I         value
# 1: 1 2.121996e-314
# 2: 1 2.470328e-323
# 3: 2 3.920509e-316
# 4: 2 2.470328e-323

更简单的命令使我的 R 从评论中崩溃:

d[-5, value, by = date]

正如 Ricardo 指出的那样，负索引和 by 的组合造成了问题。

Answer 1

更新:此问题已在 v1.8.11 中修复。来自 NEWS :

Crash or incorrect aggregate results with negative indexing in i is fixed, #2697. Thanks to Eduard Antonyan (eddi) for reporting. Tests added.