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How to convert the character values in an R data frame column to lower case?
The character values can be stored in uppercase, lowercase, or a mixture of the two. If we have values that are either in uppercase or the mixture of lower and upper then we can convert those character values to only lowercase by using tolower function. We simply need to pass the vector or column of the data frame inside the tolower function as shown in the below examples.
Example1
Consider the below data frame −
> x1<-sample(LETTERS[1:4],20,replace=TRUE) > y1<-rnorm(20) > df1<-data.frame(x1,y1) > df1
Output
x1 y1 1 C -0.1036851 2 C -0.6176530 3 B 0.5763786 4 A 0.1943794 5 C 1.1196470 6 D -1.4202033 7 A -1.9147143 8 D -1.6492836 9 B 0.2806705 10 D -1.0246326 11 B -0.1584948 12 A 0.8301300 13 C -1.1100439 14 C 0.4864598 15 C 1.3461719 16 D -2.3021691 17 D -0.8527835 18 A -0.0160726 19 A -1.3944416 20 D 1.5769472
Changing the character values in x1 to lowercase −
> df1$x1<-tolower(df1$x1) > df1
Output
x1 y1 1 c -0.1036851 2 c -0.6176530 3 b 0.5763786 4 a 0.1943794 5 c 1.1196470 6 d -1.4202033 7 a -1.9147143 8 d -1.6492836 9 b 0.2806705 10 d -1.0246326 11 b -0.1584948 12 a 0.8301300 13 c -1.1100439 14 c 0.4864598 15 c 1.3461719 16 d -2.3021691 17 d -0.8527835 18 a -0.0160726 19 a -1.3944416 20 d 1.5769472
Example2
> x2<-sample(LETTERS[1:10],20,replace=TRUE) > y2<-rpois(20,5) > df2<-data.frame(x2,y2) > df2
Output
x2 y2 1 G 4 2 D 3 3 G 2 4 E 3 5 B 6 6 I 2 7 A 8 8 F 6 9 A 7 10 F 5 11 C 10 12 G 5 13 I 4 14 H 7 15 F 4 16 A 3 17 J 3 18 I 3 19 D 6 20 F 8
Changing the character values in x2 to lowercase −
> df2$x2<-tolower(df2$x2) > df2
Output
x2 y2 1 g 4 2 d 3 3 g 2 4 e 3 5 b 6 6 i 2 7 a 8 8 f 6 9 a 7 10 f 5 11 c 10 12 g 5 13 i 4 14 h 7 15 f 4 16 a 3 17 j 3 18 i 3 19 d 6 20 f 8
Example3
> x3<-sample(LETTERS[1:2],20,replace=TRUE) > y3<-runif(20,2,5) > df3<-data.frame(x3,y3) > df3
Output
x3 y3 1 A 2.144779 2 A 4.020497 3 A 4.152795 4 A 4.579962 5 A 4.151587 6 B 3.668675 7 B 3.918459 8 B 2.326660 9 B 4.826448 10 A 4.159623 11 B 4.966475 12 B 4.159850 13 B 4.478584 14 A 2.585765 15 B 3.661653 16 B 2.836051 17 B 3.947854 18 B 3.650995 19 A 3.333785 20 A 2.147321
Changing the character values in x3 to lowercase −
> df3$x3<-tolower(df3$x3) > df3
Output
x3 y3 1 a 2.144779 2 a 4.020497 3 a 4.152795 4 a 4.579962 5 a 4.151587 6 b 3.668675 7 b 3.918459 8 b 2.326660 9 b 4.826448 10 a 4.159623 11 b 4.966475 12 b 4.159850 13 b 4.478584 14 a 2.585765 15 b 3.661653 16 b 2.836051 17 b 3.947854 18 b 3.650995 19 a 3.333785 20 a 2.147321
Updated on: 05-Mar-2021
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