R：当使用rep(..,..)复制1020个a字符变量时，结果只包含1019个重复？
在 R 环境中编程时，我使用了rep("[35,40)",1020)。这应该给我一个包含 1020 次“[35,40)”的列表。但是，结果仅包含这些元素中的 1019 个。
编程首先是在两个向量的复制中完成的，但即使我将其分开，它也不起作用。
我尝试使用不同版本的 R（R 2.11.1、R 2.9.0、R 2.10.0、R 2.7.2），但在它们中都无法正常工作。
有谁知道是否有 R 版本没有这个错误？或者我该如何解决这个问题？
所以代码如下：
> agecats
[1] "(-0.001,5]" "(5,10]" "(10,15]" "(15,20]" "(20,25]"
[6] "(25,30]" "(30,35]" "(35,40]" "(40,45]" "(45,50]"
[11] "(50,55]" "(55,60]" "(60,65]" "(65,70]" "(70,75]"
[16] "(75,80]"
> weightage<-c(0.9,0.9,2.7,3.1,8.9,10.05,10.05,10.2,10.2,9.3,9.3,8.7,7.9,3.15,3.15,1.5)
> weightage
[1] 0.90 0.90 2.70 3.10 8.90 10.05 10.05 10.20 10.20 9.30 9.30 8.70
[13] 7.90 3.15 3.15 1.50
> weightage100<-weightage*100
> weightage100
[1] 90 90 270 310 890 1005 1005 1020 1020 930 930 870 790 315 315
[16] 150
> tosamplefrom<-rep(agecats,weightage100)
> table(tosamplefrom)
tosamplefrom
(-0.001,5] (10,15] (15,20] (20,25] (25,30] (30,35] (35,40]
90 270 310 890 1005 1005 1019
(40,45] (45,50] (5,10] (50,55] (55,60] (60,65] (65,70]
1019 930 90 930 869 790 315
(70,75] (75,80]
315 150
这里我应该有 8 和 9 1020 次，但它只给出 1019 次。
金
When programming within the R environment I used rep("[35,40)",1020). This should give me a list with 1020 times "[35,40)". However, the result contains only 1019 of these elements.
The programming was first done within a replicated for two vectors, but even when I split it up it doesn't work.
What I tried is using differen versions of R (R 2.11.1, R 2.9.0, R 2.10.0, R 2.7.2) but in none of them it works properly.
Has anyone an idea if there is a version of R which doesn't have this bug? Or how I could solve this problem?
So the code for this:
> agecats
[1] "(-0.001,5]" "(5,10]" "(10,15]" "(15,20]" "(20,25]"
[6] "(25,30]" "(30,35]" "(35,40]" "(40,45]" "(45,50]"
[11] "(50,55]" "(55,60]" "(60,65]" "(65,70]" "(70,75]"
[16] "(75,80]"
> weightage<-c(0.9,0.9,2.7,3.1,8.9,10.05,10.05,10.2,10.2,9.3,9.3,8.7,7.9,3.15,3.15,1.5)
> weightage
[1] 0.90 0.90 2.70 3.10 8.90 10.05 10.05 10.20 10.20 9.30 9.30 8.70
[13] 7.90 3.15 3.15 1.50
> weightage100<-weightage*100
> weightage100
[1] 90 90 270 310 890 1005 1005 1020 1020 930 930 870 790 315 315
[16] 150
> tosamplefrom<-rep(agecats,weightage100)
> table(tosamplefrom)
tosamplefrom
(-0.001,5] (10,15] (15,20] (20,25] (25,30] (30,35] (35,40]
90 270 310 890 1005 1005 1019
(40,45] (45,50] (5,10] (50,55] (55,60] (60,65] (65,70]
1019 930 90 930 869 790 315
(70,75] (75,80]
315 150
And here I should have the 8 and 9 1020 times and it just gives 1019 times.
Kim
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这是你的问题。 10.2 无法准确表示，一切都会变得很糟糕，因为你要乘以浮点数并假设它是整数。看来 R 必须取数字的下限或仅使用 as.integer 进行转换：
无论浮点值略高于还是略低于，舍入都会起作用。以下更改确实解决了该问题。
阅读R Inferno（像这样的浮点问题并不限于以R为例，我只是在python中复制了它）
This is your problem. 10.2 can't be represented exactly and everything is going to hell because you're multiplying a floating point number and assuming it's an integer. It appears that R must be taking the floor of the number or just using as.integer for the conversion:
Rounding will work whether the floating point value is slightly above or slight below. The following change does fix the problem.
Read the R Inferno (floating point problems like this are not exclusive to R, for example, I just replicated it in python)