How to find the column maximum if some columns are categorical in R data frame?

To find the column maximum if some columns are categorical in R data frame, we can follow the below steps −

• First of all, create a data frame.

• Then, use numcolwise function from plyr package to find the column maximum if some columns are categorical.

Example 1

Create the data frame

Let’s create a data frame as shown below −

Group<-sample(c("I","II","III","IV"),25,replace=TRUE) Num1<-sample(1:50,25) Num2<-sample(1:50,25) df1<-data.frame(Group,Num1,Num2) df1

Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

 Group Num1 Num2 1 III 43 36 2 I 5 22 3 IV 3 23 4 II 40 40 5 IV 47 33 6 II 12 3 7 II 31 21 8 IV 34 20 9 I 41 44 10 II 7 8 11 II 35 45 12 III 50 25 13 III 19 16 14 III 11 34 15 I 1 28 16 III 21 31 17 IV 9 47 18 III 15 9 19 I 23 11 20 III 45 24 21 I 37 26 22 I 13 32 23 I 27 30 24 II 2 10 25 I 48 12

Find the column maximum if some columns are categorical

Using numcolwise function from plyr package to find the column maximum of numerical columns in the data frame df1 −

Group<-sample(c("I","II","III","IV"),25,replace=TRUE) Num1<-sample(1:50,25) Num2<-sample(1:50,25) df1<-data.frame(Group,Num1,Num2) library(plyr) numcolwise(max)(df1)

Output

  Num1 Num2 1  50 47

Example 2

Create the data frame

Let’s create a data frame as shown below −

Categories<-sample(c("First","Second","Third"),25,replace=TRUE) Score<-sample(1:10,25,replace=TRUE) Price<-sample(1:5,25,replace=TRUE) df2<-data.frame(Categories,Score,Price) df2

Output

On executing, the above script generates the below output(this output will vary on your system due to randomization) −

   Categories Score Price 1  Third      6      1 2  Second     7      1 3  Second     5      5 4  First      8      3 5  Third      5      2 6  First      9      2 7  Third      6      5 8  First      9      4 9  First      4      1 10 Second     4      5 11 Second     2      1 12 First      9      3 13 Second     4      3 14 First      4      2 15 Third      5      4 16 Third      2      5 17 First      1      4 18 First      2     1 19 Third      2 5 20 Second     1 1 21 Third      7 1 22 Second     4 2 23 First     10 1 24 Third      6 4 25 First      8 4

Find the column maximum if some columns are categorical

Using numcolwise function from plyr package to find the column maximum of numerical columns in the data frame df2−

Categories<-sample(c("First","Second","Third"),25,replace=TRUE) Score<-sample(1:10,25,replace=TRUE) Price<-sample(1:5,25,replace=TRUE) df2<-data.frame(Categories,Score,Price) library(plyr) numcolwise(max)(df2)

Output

 Score Price 1 10 5