operator ==在data.table的逻辑列中不一致 [英] Operator == inconsistent in logical columns in data.table

问题描述

请参阅以下可重现的示例：

Please see the following reproducible example:

library(data.table)
set.seed(123)
DT <- data.table(A=rep(0.3,10000))
DT[, B := runif(.N) < A]
DT[B == T, .N]
# [1] 3005
DT[, summary(B)]
#    Mode   FALSE    TRUE    NA's
# logical    6995    3005       0

一切正常，TRUE值的计数与2方法。现在用新的替换B。

Everything looks fine and the count of "TRUE" values is the same for the 2 methods. Now replace col B with a new one.

DT[, B := runif(.N) < A]
DT[B == T, .N]
# [1] 3331
DT[, summary(B)]
#    Mode   FALSE    TRUE    NA's
# logical    6981    3019       0 

B列中的'T'计数不同！它是同一列，但一种方法给出3331TRUE值，其他3019。

The count of 'T' in the column B is different!!! It is the same column but one method gives 3331 "TRUE" values and the other 3019.

当绕过==时

DT[B != F, .N]
# [1] 3019
DT[, summary(B)]
#    Mode   FALSE    TRUE    NA's
# logical    6981    3019       0 

这是正确的

我可以用Windows 8.1 x64上的data.table v1.94和1.9.5重现它。

I can reproduce it with data.table v1.94 and 1.9.5 on Windows 8.1 x64.

这是一个更容易重现的例子，不带 runif（）。

Here's a much easier reproducible example without runif().

require(data.table) ## 1.9.4+
DT = data.table(x = 1:5)
DT[, y := x <= 2L]
#    x     y
# 1: 1  TRUE
# 2: 2  TRUE
# 3: 3 FALSE
# 4: 4 FALSE
# 5: 5 FALSE

DT[y == TRUE, .N]
# [1] 2             <~~~~~~ correct result.

DT[, y := x <= 3L]
#    x     y
# 1: 1  TRUE
# 2: 2  TRUE
# 3: 3  TRUE
# 4: 4 FALSE
# 5: 5 FALSE

DT[y == TRUE, .N]
# [1] 2             <~~~~~~ incorrect result, should be 3!

推荐答案

现在固定在 v1.9.5 在GitHub上。

Now fixed in v1.9.5 on GitHub.

：= 和 set * 现在删除辅助密钥（v1.9.4中的新） ：= 或设置* $ c> DT [x == y] c>不需要选项（datatable.auto.index = FALSE）。只有 setkey（）正确放置辅助键。添加了23个测试。感谢user36312进行报告，＃885 。

:= and set* now drop secondary keys (new in v1.9.4) so that DT[x==y] works again after a := or set* without needing options(datatable.auto.index=FALSE). Only setkey() was dropping secondary keys correctly. 23 tests added. Thanks to user36312 for reporting, #885.

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