如何重命名data.frame中的單個列？

本文翻譯自：How to rename a single column in a data.frame?

I know if I have a data frame with more than 1 column, I can use 我知道如果我有一個多於一列的數據框，我可以使用

colnames(x) <- c("col1","col2")

to rename the columns. 重命名列。 How do I do this if it's just one column? 如果只有一欄，該怎麼辦？ Meaning a vector or data frame with only one column in it. 表示其中僅包含一列的向量或數據幀。

Example: 例：

trSamp <- data.frame(sample(trainer$index, 10000))
head(trSamp )
#   sample.trainer.index..10000.
# 1                      5907862
# 2                      2181266
# 3                      7368504
# 4                      1949790
# 5                      3475174
# 6                      6062879

ncol(trSamp)
# [1] 1
class(trSamp)
# [1] "data.frame"
class(trSamp[1])
# [1] "data.frame"
class(trSamp[,1])
# [1] "numeric"
colnames(trSamp)[2] <- "newname2"
# Error in names(x) <- value : 
#   'names' attribute [2] must be the same length as the vector [1]

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#1樓

參考：https://stackoom.com/question/VbNk/如何重命名data-frame中的單個列

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#2樓

您也可以嘗試從“ Hmisc”包中獲取“ upData”。

library(Hmisc)

trSamp = upData(trSamp, rename=c(sample.trainer.index..10000. = 'newname2'))

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#3樓

This is a generalized way in which you do not have to remember the exact location of the variable: 這是一種通用的方式，您不必記住變量的確切位置：

# df = dataframe
# old.var.name = The name you don't like anymore
# new.var.name = The name you want to get

names(df)[names(df) == 'old.var.name'] <- 'new.var.name'

This code pretty much does the following: 此代碼幾乎可以執行以下操作：

1. names(df) looks into all the names in the df names(df)的外觀到在所有的名字df
2. [names(df) == old.var.name] extracts the variable name you want to check [names(df) == old.var.name]提取您要檢查的變量名
3. <- 'new.var.name' assigns the new variable name. <- 'new.var.name'分配新的變量名稱。

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#4樓

This can also be done using Hadley's plyr package, and the rename function. 這也可以使用Hadley的plyr包和rename功能來完成。

library(plyr) 
df <- data.frame(foo=rnorm(1000)) 
df <- rename(df,c('foo'='samples'))

You can rename by the name (without knowing the position) and perform multiple renames at once. 您可以按名稱重命名（不知道位置），並一次執行多個重命名。 After doing a merge, for example, you might end up with: 例如，進行合併後，您可能會得到以下結果：

  letterid id.x id.y
1       70    2    1
2      116    6    5
3      116    6    4
4      116    6    3
5      766   14    9
6      766   14   13

Which you can then rename in one step using: 然後您可以使用以下步驟一步重命名：

letters <- rename(letters,c("id.x" = "source", "id.y" = "target"))

  letterid source target
1       70      2      1
2      116      6      5
3      116      6      4
4      116      6      3
5      766     14      9
6      766     14     13

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#5樓

This is an old question, but it is worth noting that you can now use setnames from the data.table package. 這是一個老問題，但值得注意的是，您現在可以使用setnames從data.table包。

library(data.table)

setnames(DF, "oldName", "newName")

# or since the data.frame in question is just one column: 
setnames(DF, "newName")

# And for reference's sake, in general (more than once column)
nms <- c("col1.name", "col2.name", etc...)
setnames(DF, nms)

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#6樓

I like the next style for rename dataframe column names one by one. 我喜歡一種用於逐一重命名數據框列名稱的樣式。

colnames(df)[which(colnames(df) == 'old_colname')] <- 'new_colname'

where 哪裏

which(colnames(df) == 'old_colname')

returns by the index of the specific column. 通過特定列的索引返回。