R 中的数字列名 [英] numeric column names in R

问题描述

我有一个如下的数据框:

I have a data frame as follows:

structure(list(`104` = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, 
NA, NA, NA, NA, NA, NA, "yes", NA, NA, NA, NA), `15` = c(NA, 
NA, NA, NA, ">= 4.0", ">= 4.0", NA, "~ 2", "~ 2", "~ 2", "~ 2", 
"~ 2", "~ 2", "< 2.2", "~2.75", NA, "~2.75", "~2.75", "~2.75", 
"~2.75")), .Names = c("104", "15"), row.names = 45:64, class = "data.frame")

我知道使用数字列名不是最佳做法，但在这种情况下是必要的.我一直在通过检索带有反引号的列来操作我的数据框 `

I know that it is not best practices to have numeric column names, however it is necessary in this circumstance. I have been manipulating my data frame through retrieving columns with a backtick `

不幸的是，我在上面的数据框中发现了一些有趣的东西.

Unfortunately, I found something funny in the above data frame.

> table(testtest$`10`)

 yes 
  1 
> 

但是没有列名称为10，所以看起来是在检索

However there is no column with a name of 10, so it looks like it is retrieving

> table(testtest$`104`)

 yes 
 1 
> 

我现在很紧张，不相信这会在我不知道其他列(例如 41 和 4100)的情况下再次弹出.

I am nervous now, and do not trust that this may pop up again without my knowing for other columns such as 41 and 4100.

任何解释都会有帮助！谢谢

Any explanation would be helpful! Thanks

推荐答案

这是由于部分匹配.为避免这种情况，请使用 [[ 提取列

This is due to the partial matching. To avoid it, use [[ to extract the columns

testtest[["10"]]
#NULL

而正确的列名给出输出

 testtest[["104"]]
 #[1] NA    NA    NA    NA    NA    NA    NA    NA    NA    NA    NA  
 #[12] NA    NA    NA    NA    "yes" NA    NA    NA    NA 

根据?"$"

[[ 和 $ 都选择列表中的单个元素.主要区别是 $ 不允许计算索引，而 [[ 允许.x$name 是等价于 x[["name", exact = FALSE]].此外，部分匹配[[ 的行为可以使用精确参数进行控制.

Both [[ and $ select a single element of the list. The main difference is that $ does not allow computed indices, whereas [[ does. x$name is equivalent to x[["name", exact = FALSE]]. Also, the partial matching behavior of [[ can be controlled using the exact argument.

<小时>

一般来说，最好不要有数字列名或以数字开头的名称.我们可以使用方便的函数 make.names

names(testtest) <- make.names(names(testtest))
names(testtest)
#[1] "X104" "X15" 

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