如何从R数据帧的列值中删除下划线之后的值之前的所有内容？

如果R数据帧中的列包含用下划线分隔的字符串值，并且扩展了也包含公用值的列值的大小，则明智的做法是一次从所有值中删除下划线符号以及常见。这将帮助我们正确读取数据，并使分析变得容易。为此，我们可以使用gsub函数

请看以下数据帧-

示例

set.seed(191)
ID<-c("ID_1","ID_2","ID_3","ID_4","ID_5","ID_6","ID_7","ID_8","ID_9","ID_10","ID_11","ID_12","ID_13","ID_14","ID_15","ID_16","ID_17","ID_18","ID_19","ID_20")
Salary<-sample(20000:50000,20)
df1<-data.frame(ID,Salary)
df1

输出结果

   ID   Salary
1  ID_1  33170
2  ID_2  22747
3  ID_3  42886
4  ID_4  22031
5  ID_5  45668
6  ID_6  32584
7  ID_7  34779
8  ID_8  20471
9  ID_9  38689
10 ID_10 29660
11 ID_11 49664
12 ID_12 24284
13 ID_13 36537
14 ID_14 37693
15 ID_15 30265
16 ID_16 36004
17 ID_17 48247
18 ID_18 20750
19 ID_19 27400
20 ID_20 20553

从列ID中的ID值中删除下划线之前和包括下划线在内的所有内容-

示例

df1$ID<-gsub("^.*\\_","",df1$ID)
df1

输出结果

   ID Salary
1  1  48769
2  2  26002
3  3  37231
4  4  24437
5  5  43311
6  6  47494
7  7  21029
8  8  28069
9  9  41108
10 10 29363
11 11 23371
12 12 25898
13 13 42434
14 14 22210
15 15 48969
16 16 21640
17 17 36175
18 18 21210
19 19 43374
20 20 29367

让我们看另一个例子-

示例

Group<-c("GRP_1","GRP_2","GRP_3","GRP_4","GRP_5","GRP_6","GRP_7","GRP_8","GRP_9","GRP_10","GRP_11","GRP_12","GRP_13","GRP_14","GRP_15","GRP_16","GRP_17","GRP_18","GRP_19","GRP_20")
 Ratings<-sample(0:10,20,replace=TRUE)
df2<-data.frame(Group,Ratings)
df2

输出结果

 Group Ratings
1  GRP_1  6
2  GRP_2  9
3  GRP_3  7
4  GRP_4 10
5  GRP_5 10
6  GRP_6  9
7  GRP_7  9
8  GRP_8  3
9  GRP_9  2
10 GRP_10 0
11 GRP_11 3
12 GRP_12 7
13 GRP_13 6
14 GRP_14 10
15 GRP_15 1
16 GRP_16 3
17 GRP_17 10
18 GRP_18 2
19 GRP_19 9
20 GRP_20 0

从组Group的GRP值中删除下划线之前和包括下划线在内的所有内容-

示例

df2$Group<-gsub("^.*\\_","",df2$Group)
df2

输出结果

   Group Ratings
1   1     4
2   2     8
3   3     7
4   4     0
5   5    10
6   6    10
7   7     5
8   8     4
9   9     3
10 10     7
11 11     4
12 12     4
13 13     3
14 14    10
15 15     7
16 16     2
17 17     3
18 18     8
19 19     9
20 20     5