使用get()在R数据表中找不到数值列
使用get()在R数据表中找不到数值列
提问于 2020-06-12 00:01:54
我有一个包含几个数字列名的数据表，用于即时2020-4和2020-5。我将其称为Nouvelle_periode = "2020-5"和Ancienne_periode = "2020-4"，我设法通过使用前面提到的get来处理这些列中的内容。
但是删除一列似乎不起作用：
这是可行的：Test_2 <- Test[,Revision:=get(Nouvelle_periode) - get(Ancienne_periode)]
但这不是：Test_3 <- Test_2 [,get(Ancienne_periode):=NULL] (我得到错误object 2020-4 not found，即使它仍然是
我也不知道为什么。
以下是MWE：
library(data.table)
Nouvelle_periode = "2020-5"
Ancienne_periode = "2020-4"
Test <- data.table(Zone = c("Allemagne", "Allemagne", "Allemagne",
"Allemagne", "Espagne", "Espagne", "Espagne", "Espagne", "Etats-Unis",
"Etats-Unis", "Etats-Unis", "Etats-Unis", "France", "France",
"France", "France", "Italie", "Italie", "Italie", "Italie", "Japon",
"Japon", "Japon", "Japon", "Monde", "Monde", "Monde", "Monde",
"Royaume-Uni", "Royaume-Uni", "Royaume-Uni", "Royaume-Uni", "Zone euro",
"Zone euro", "Zone euro", "Zone euro"), Periode = c("2020", "2020",
"2021", "2021", "2020", "2020", "2021", "2021", "2020", "2020",
"2021", "2021", "2020", "2020", "2021", "2021", "2020", "2020",
"2021", "2021", "2020", "2020", "2021", "2021", "2020", "2020",
"2021", "2021", "2020", "2020", "2021", "2021", "2020", "2020",
"2021", "2021"), Grandeur = c("IPC", "PIB", "IPC", "PIB", "IPC",
"PIB", "IPC", "PIB", "IPC", "PIB", "IPC", "PIB", "IPC", "PIB",
"IPC", "PIB", "IPC", "PIB", "IPC", "PIB", "IPC", "PIB", "IPC",
"PIB", "IPC", "PIB", "IPC", "PIB", "IPC", "PIB", "IPC", "PIB",
"IPC", "PIB", "IPC", "PIB"), `2020-4` = c(0.7, -5, 1.4, 4.5,
-0.4, -5.7, 1.3, 5.2, 0.8, -4, 1.8, 3.9, 0.4, -5.4, 1.3, 5.1,
-0.2, -7.5, 0.6, 4.5, -0.1, -3.3, 0.2, 2.1, 2.1, -2.1, 2.4, 4.4,
1, -5.4, 1.6, 4.7, 0.4, -5.7, 1.3, 5.4),
`2020-5` = c(0.6, -6.3, 1.4, 5.2, -0.4, -9.1, 1, 6.7, 0.7, -5.4, 1.8, 4.3, 0.3, -8.2,
1.2, 6.7, -0.2, -9.9, 0.6, 6.3, -0.4, -5.5, 0.1, 2.4, 2, -4.1, 2.3, 5.1, 1, -7.9, 1.4, 6.1, 0.3, -7.9, 1.1, 6.2))
Test_2 <- Test[,Revision:=get(Nouvelle_periode) - get(Ancienne_periode)]
Test_3 <- Test_2 [,get(Ancienne_periode):=NULL]回答 1
Stack Overflow用户
回答已采纳
发布于 2020-06-12 00:06:06
不需要get，在:=操作员的lhs上使用c(...)：
head( Test_2 [,c(Ancienne_periode) := NULL] )
# Zone Periode Grandeur 2020-5 Revision
# 1: Allemagne 2020 IPC 0.6 -0.1
# 2: Allemagne 2020 PIB -6.3 -1.3
# 3: Allemagne 2021 IPC 1.4 0.0
# 4: Allemagne 2021 PIB 5.2 0.7
# 5: Espagne 2020 IPC -0.4 0.0
# 6: Espagne 2020 PIB -9.1 -3.4页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/62328519
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