Sum of rows in R based on condition

To find the sum of rows in R based on a condition, we select only the rows that match the condition and then use the sum() function to add their values.

Method 1: Sum of Rows Based on a Single Condition

We calculate the sum of specific row values filtered by one logical condition.

Example: 1

• team, captain, centuries: vectors used to define data
• data.frame(): creates the data frame from vectors
• df: name of the data frame
• print(): displays the data frame or result
• with(): applies expressions within a data frame context
• sum(): calculates the total
• [captain == 'dhoni']: filters rows where captain equals "dhoni"

Output:

Example: 2

• name, age, place: vectors used to define the data
• df: name of the data frame
• place == "guntur": filters rows where the place equals "guntur"
• sum(age[...]): sums the age values matching the condition

Output:

Method 2: Sum of Rows Based on Multiple Conditions

We calculate the sum by applying multiple logical filters simultaneously.

Example: 1

• employee, emp_id, salary: columns in the data frame
• emp_id > 7: filters rows with emp_id greater than 7
• employee == 'x': filters rows where employee is "x"
• &: logical AND operator to combine conditions
• sum(...): computes total for matching rows

Output:

Example: 2

• vec1, vec2, vec3: vectors used to create the data frame
• vec2 == "a" & vec3 == "pk": compound condition for filtering rows
• sum(vec1[...]): computes the total of vec1 where both conditions are met

Output:

We learned how to calculate the sum of rows based on conditions in R programming language.