How to find the table of mean of a numerical column based on two factors in R data frame?

To find the table of mean of a numerical column based on two factors in R data frame, we can follow the below steps −

• First of all, create a data frame with two factor and one numerical column.

• Then, find the table of mean of numerical column based on factor columns using tapply function.

Example1

Let’s create a data frame as shown below −

 Live Demo

Group1<-sample(c("I","II","III"),25,replace=TRUE)
Group2<-sample(c("Low","Medium","High"),25,replace=TRUE)
Score<-sample(1:100,25)
df<-data.frame(Group1,Group2,Score)
df

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

Output

  Group1 Group2 Score
1  III    Low    3
2  II    High    45
3  III  Medium   17
4  III    Low    50
5  I    Medium   40
6  III    Low    77
7  II   Medium   1
8  I     High    73
9  II    High    62
10 I     High    5
11 II   Medium   88
12 I     High    98
13 I    Medium   60
14 II    Low     84
15 III   Low     12
16 I    Medium   66
17 III  Medium   23
18 II    High    61
19 I     High    15
20 III   High    94
21 II   Medium   87
22 II   Medium   37
23 I    Medium   11
24 I     High    26
25 I    Medium   93

Find the table of mean based on two factor columns

Using tapply function with mean function to find the mean of Score column based on Group1 and Group2 columns −

 Live Demo

Group1<-sample(c("I","II","III"),25,replace=TRUE)
Group2<-sample(c("Low","Medium","High"),25,replace=TRUE)
Score<-sample(1:100,25)
df<-data.frame(Group1,Group2,Score)
tapply(Score,list(df$Group1,df$Group2),mean)

Output

    High Low Medium
I   43.4  NA  54.00
II  56.0 84.0 53.25
III 94.0 35.5 20.00

Example2

Let’s create a data frame as shown below −

 Live Demo

f1<-sample(c("Male","Female"),25,replace=TRUE)
f2<-sample(c("Slow","Fast"),25,replace=TRUE)
Result<-sample(1:100,25)
dat<-data.frame(f1,f2,Result)
dat

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

Output

   f1  f2  Result
1 Male Slow   37
2 Male Fast   13
3 Female Fast 87
4 Male Slow   36
5 Male Fast   22
6 Female Fast 86
7 Male Slow   42
8 Female Fast 17
9 Female Slow 46
10 Male Fast  27
11 Female Fast 49
12 Male Slow   24
13 Male Fast   53
14 Male Fast    67
15 Female Fast 28
16 Male Fast    6
17 Female Slow 61
18 Male Slow   90
19 Male Fast   12
20 Male Fast   47
21 Female Fast 9
22 Female Fast 66
23 Male Fast   73
24 Male Slow   14
25 Female Fast 81

Find the table of mean based on two factor columns

Using tapply function with mean function to find the mean of Result column based on f1 and f2 columns −

 Live Demo

f1<-sample(c("Male","Female"),25,replace=TRUE)
f2<-sample(c("Slow","Fast"),25,replace=TRUE)
Result<-sample(1:100,25)
dat<-data.frame(f1,f2,Result)
tapply(Result,list(dat$f1,dat$f2),mean)

Output

         Fast   Slow
Female 52.87500 53.5
Male   35.55556 40.5