英文:
data.table ordering gives unexpected results inconsistent with base R
问题
我注意到了一些与 data.table 有关的奇怪行为。似乎涉及到反引号 (`) 的使用。我已经准备了一个简单的示例：
library(data.table)
data.table(v1 = c("2", "1", "10"))[order(v1)]
#> v1
#> 1: 1
#> 2: 10
#> 3: 2
data.table(v1 = c("`2`", "`1`", "`10`"))[order(v1)]
#> v1
#> 1: `10`
#> 2: `1`
#> 3: `2`
c("2", "1", "10")[order(c("2", "1", "10"))]
#> [1] "1" "10" "2"
c("`2`", "`1`", "`10`")[order(c("`2`", "`1`", "`10`"))]
#> [1] "`1`" "`10`" "`2`"
创建于2023-05-25，使用 reprex v2.0.2。
正如您所看到的，使用反引号会改变行的顺序，而基本的 R 不会显示这种行为（给出了预期的结果）。
这是一个 bug 还是一个特性？
英文:
I have noticed some odd behaviour with data.table. It seems to involve the use of backticks (`). I have prepared a simple example here:
library(data.table)
data.table(v1 = c("2", "1", "10"))[order(v1)]
#> v1
#> 1: 1
#> 2: 10
#> 3: 2
data.table(v1 = c("`2`", "`1`", "`10`"))[order(v1)]
#> v1
#> 1: `10`
#> 2: `1`
#> 3: `2`
c("2", "1", "10")[order(c("2", "1", "10"))]
#> [1] "1" "10" "2"
c("`2`", "`1`", "`10`")[order(c("`2`", "`1`", "`10`"))]
#> [1] "`1`" "`10`" "`2`"
<sup>Created on 2023-05-25 with reprex v2.0.2</sup>
As you can see, using backticks changes the order of rows. Whereas base R doesn't show this behaviour (gives the expected result).
Is this a bug or a feature?
答案1
得分: 1
这只是 base::order 和 data.table::order 之间的差异。?data.table::order 手册中指出它们是不同的。
> 使用 C 语言环境使得 data.table 中排序的行为在会话和地区设置间更一致。base::order 的行为取决于 R 会话地区设置的假设。
data.table(v1 = c("2", "1", "10"))[ 按照(v1) 排序 ]
v1
1: 10
2: 1
3: 2
data.table(v1 = c("2", "1", "10"))[ base::order(v1) ]
v1
1: 1
2: 10
3: 2
英文:
This is just a difference between base::order and data.table::order. The manuals for ?data.table::order, says they are different.
> Using C-locale makes the behaviour of sorting in data.table more consistent across sessions and locales. The behaviour of base::order depends on assumptions about the locale of the R session.
data.table(v1 = c("`2`", "`1`", "`10`"))[ order(v1) ]
# v1
# 1: `10`
# 2: `1`
# 3: `2`
data.table(v1 = c("`2`", "`1`", "`10`"))[ base::order(v1) ]
# v1
# 1: `1`
# 2: `10`
# 3: `2`
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