data.table中重复的colnames的setnames-Java 学习之路

由于某些原因（无关紧要），excel导入数据帧中的colnames具有下面给出的重复项（DT是从数据帧DF转换的数据表） . 但是，这些是唯一的名称，因此需要使用 setnames .

DF<-structure(list(X1 = c("", "15 May 2014", "16 May 2014", "18 May 2014", 
"19 May 2014"), X2 = c(NaN, 746.18, 746.18, 744.34, 739.95), 
X3 = c(NaN, 549.9, 549.9, 546.5, 549.65), X1 = c(NaN, 406.57, 
406.57, 406.66, 404.73), X1 = c(NaN, 1788.86, 1788.86, 1767.69, 
1772.34), X1 = c(NaN, 2286, 2286, 2302.37, 2313.14), X2 = c(NaN, 
3639.25, 3639.25, 3622.08, 3569.53), X3 = c(NaN, 1160.13, 
1160.13, 1144.77, 1129.72), X1 = c(NaN, 182.83, 182.83, 182.83, 
182.83), X2 = c(NaN, 787.13, 787.13, 775.39, 764.82), X1 = c(NaN, 
853.2, 853.2, 849.67, 844.49)), .Names = c("X1", "X2", "X3", 
"X1", "X1", "X1", "X2", "X3", "X1", "X2", "X1"), class = c("data.table", 
"data.frame"), row.names = c(NA, -5L))

DT<-as.data.table(DF)

 >DT

                X1     X2     X3     X1      X1      X1      X2      X3     X1     X2     X1
    1:                NaN    NaN    NaN     NaN     NaN     NaN     NaN    NaN    NaN    NaN
    2: 15 May 2014 746.18 549.90 406.57 1788.86 2286.00 3639.25 1160.13 182.83 787.13 853.20
    3: 16 May 2014 746.18 549.90 406.57 1788.86 2286.00 3639.25 1160.13 182.83 787.13 853.20
    4: 18 May 2014 744.34 546.50 406.66 1767.69 2302.37 3622.08 1144.77 182.83 775.39 849.67
    5: 19 May 2014 739.95 549.65 404.73 1772.34 2313.14 3569.53 1129.72 182.83 764.82 844.49

所以，我决定使用 setnames 更改这些colnames，但是我收到以下错误（很明显）：

new_names<-c("Date","BOD","DO","FI","HT","HY","IN","MA","SE","OR","RA")
 old_names<-names(DT)
 setnames(DT, old_names, new_names)

 Error in setnames(DT, old_names, new_names) : 
  Some duplicates exist in 'old': X1,X1,X1,X2,X3,X1,X2,X1

所以，我使用data.frame改变colnames的方式

names(DT)<-new_names # this doesn't give any error but still gives warnings

Warning message:
In `names<-.data.table`(`*tmp*`, value = c("Date", "BOD", "DO",  :
  The names(x)<-value syntax copies the whole table. This is due to <- in R itself. Please change to setnames(x,old,new) which does not copy and is faster. See help('setnames'). You can safely ignore this warning if it is inconvenient to change right now. Setting options(warn=2) turns this warning into an error, so you can then use traceback() to find and change your names<- calls.
> DT
          Date    BOD     DO     FI      HT      HY      IN      MA     SE     OR     RA
1:                NaN    NaN    NaN     NaN     NaN     NaN     NaN    NaN    NaN    NaN
2: 15 May 2014 746.18 549.90 406.57 1788.86 2286.00 3639.25 1160.13 182.83 787.13 853.20
3: 16 May 2014 746.18 549.90 406.57 1788.86 2286.00 3639.25 1160.13 182.83 787.13 853.20
4: 18 May 2014 744.34 546.50 406.66 1767.69 2302.37 3622.08 1144.77 182.83 775.39 849.67
5: 19 May 2014 739.95 549.65 404.73 1772.34 2313.14 3569.53 1129.72 182.83 764.82 844.49

所以，我想知道当colnames不唯一时是否有data.table（唯一）更改colnames的方式（同样，这是因为数据是从excel导入的） .

2 回答

0
你可以省略old_names：
```
setnames(DT, new_names)
```
将工作假设 new_names 具有正确顺序的所有名称 . 从 ?setnames ：

setnames（x，old，new）：old：提供new时，要更改列名的字符名称或数字位置 . 如果未提供new，则新列名称必须与列数相同 . 见例子 .
回复于 2024-05-02T15:29:05+08:00

我遇到了同样的问题，但我不关心列可以得到什么新名称，所以我只需要唯一的名称 . 将 make.unique 或 make.names （如建议的here）与 setnames （由@BrodieG above指出）组合解决了我的问题：

# considering your DT object:
setnames(DT, make.unique(names(DT)))
# The new column names are:
names(DT)
## [1] "X1"   "X2"   "X3"   "X1.1" "X1.2" "X1.3" "X2.1" "X3.1" "X1.4" "X2.2" "X1.5"
# Same can be achieved with:
setnames(DT, make.names(names(DT), unique = TRUE))

回复于 2024-05-02T15:29:05+08:00

data.table中重复的colnames的setnames

2 回答

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