How to convert the data type of all columns from integer to factor in R?

To convert the data type of all columns from integer to factor, we can use lapply function with factor function.

For example, if we have a data frame called df which has all integer columns then we can use the below given command to convert all columns data type to factor −

df<-data.frame(lapply(df,factor))

Example 1

Following snippet creates a sample data frame −

x1<-rpois(20,1)
x2<-rpois(20,2)
df1<-data.frame(x1,x2)
df1

The following dataframe is created −

   x1 x2
1  1  4
2  3  0
3  0  1
4  1  1
5  1  2
6  1  1
7  1  2
8  3  2
9  2  3
10 3  5
11 1  4
12 0  1
13 2  0
14 2  2
15 0  1
16 3  0
17 0  2
18 0  3
19 1  1
20 0  3

To convert the data type of all columns from integer to factor, add the following code to the above snippet −

x1<-rpois(20,1)
x2<-rpois(20,2)
df1<-data.frame(x1,x2)
str(df1)

Output

If you execute all the above given snippets as a single program, it generates the following output −

'data.frame': 20 obs. of 2 variables:
$ x1: int 1 3 0 1 1 1 1 3 2 3 ...
$ x2: int 4 0 1 1 2 1 2 2 3 5 ...

To convert data type of columns in df1 to factor, add the following code to the above snippet −

x1<-rpois(20,1)
x2<-rpois(20,2)
df1<-data.frame(x1,x2)
df1<-data.frame(lapply(df1,factor))
str(df1)

Outpu

If you execute all the above given snippets as a single program, it generates the following output −

'data.frame': 20 obs. of 2 variables:
$ x1: Factor w/ 4 levels "0","1","2","3": 2 4 1 2 2 2 2 4 3 4 ...
$ x2: Factor w/ 6 levels "0","1","2","3",..: 5 1 2 2 3 2 3 3 4 6 ...

Example 2

Following snippet creates a sample data frame −

y1<-sample(0:1,20,replace=TRUE)
y2<-sample(1:4,20,replace=TRUE)
df2<-data.frame(y1,y2)
df2

The following dataframe is created −

   y1 y2
1  0  2
2  1  3
3  0  2
4  0  2
5  1  3
6  0  3
7  0  2
8  1  3
9  0  4
10 0  1
11 0  4
12 0  4
13 0  1
14 1  2
15 0  1
16 0  1
17 1  4
18 1  2
19 1  3
20 1  2

To convert the data type of all columns from integer to factor, add the following code to the above snippet −

y1<-sample(0:1,20,replace=TRUE)
y2<-sample(1:4,20,replace=TRUE)
df2<-data.frame(y1,y2)
str(df2)

Output

If you execute all the above given snippets as a single program, it generates the following output −

'data.frame': 20 obs. of 2 variables:
$ y1: int 0 1 0 0 1 0 0 1 0 0 ...
$ y2: int 2 3 2 2 3 3 2 3 4 1 ...

To convert data type of columns in df2 to factor, add the following code to the above snippet −

y1<-sample(0:1,20,replace=TRUE)
y2<-sample(1:4,20,replace=TRUE)
df2<-data.frame(y1,y2)
df2<-data.frame(lapply(df2,factor))
str(df2)

Output

If you execute all the above given snippets as a single program, it generates the following output −

'data.frame': 20 obs. of 2 variables:
$ y1: Factor w/ 2 levels "0","1": 1 2 1 1 2 1 1 2 1 1 ...
$ y2: Factor w/ 4 levels "1","2","3","4": 2 3 2 2 3 3 2 3 4 1 ...

Nizamuddin Siddiqui

Updated on 12-Nov-2021 07:39:37

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