How to Select Rows by Condition in R

Using the subset() function in R, we can select rows by conditions specified in the square bracket notation for the data frame. We can specify the logical condition with operators to select rows by the condition in R.

The Subsetting data frame returns a subset of the data frame which meets the condition.

subset syntax:

subset(x, ...)

where x = data frame object to be subsetted.

In this tutorial, we will discuss how to select rows by the condition in R, subset rows with filter in R.

Select Rows in R using subset

Using the subset() function in R, we can select the rows from a data frame in R based on condition.

Let’s practice with an example to select a row from a data frame in R.

Create a data frame using the data.frame() function.

# Create a data frame
emp_info <- data.frame(
  id = c(1,2,3,4,5,6),
  name = c("Henry","Gary","Sam","Julie","Kim","Chris"),
  age = c(28,24,29,25,23,24),
  salary = c(4500,4000,5500,3650,3400,3800)
)
# Print data frame
emp_info

In the above R code, it creates a data frame of 4 columns and 6 rows and prints the output as below.

 id  name age salary
1  1 Henry  28   4500
2  2  Gary  24   4000
3  3   Sam  29   5500
4  4 Julie  25   3650
5  5   Kim  23   3400
6  6 Chris  24   3800

Let’s select a row in R where the column matches the condition.

# Filter the rows based on the condition
subset(emp_info, emp_info$name == 'Gary')

In the above R code, we have used the subset() function to specify the data frame to be subsetted and select rows where name == Gary

The output of the above R code is:

  id name age salary
2  2 Gary  24   4000

Another way to filter rows from a data frame is by specifying the name of the data frame and condition.

# Filter out rows from a data frame
subset(emp_info,name == 'Gary')

The output of the above R code select row from R based on a condition where employee name is equal to Gary

  id name age salary
2  2 Gary  24   4000

Use subset to Select Rows in R based on Condition

Let’s consider an example to filter rows from a data frame based on the conditions using the subset function in R.

Use the above emp_info data frame for illustration purposes.

Let’s select rows from a data frame where salary is greater than 4000

subset(emp_info, emp_info$salary > 4000)

In the above R code, the subset function in R takes the data frame as input and filter the rows from a data frame where salary is greater than 4000.

The output of the above R code selects one more row from a data frame where salary is greater than 4000.

  id  name age salary
1  1 Henry  28   4500
3  3   Sam  29   5500

Filter Rows in Data Frame using dplyr

Using the filter function of the dplyr package, we can filter the rows from a data frame.

Let’s use the above data frame to select rows from a data frame using filter() from the dplyr package.

filter(emp_info,salary==5500)

In the above filter function, it takes a data frame and logical condition as an input to filter out the rows in a data frame.

The output of the above R code is:

  id name age salary
1  3  Sam  29   5500

Conclusion

I hope the above article on how to select rows by the condition in R is helpful to you.

Using the subset() function and filter() function of the dplyr package, we can select one or more rows from a data frame based on the condition.