Compute the Sum of Rows of a Matrix or Array in R Programming – rowSums Function

rowSums Function in R

rowSums() function in R Programming Language is used to compute the sum of rows of a matrix or an array.

Syntax:

rowSums(x, na.rm = FALSE, dims = 1)

Parameters:

x: array or matrix

dims: Integer: Dimensions are regarded as ‘rows’ to sum over. It is over dimensions dims+1,…

Compute the Sum of Rows of a Matrix in R Programming

We will create one simple matrix and with the help of rowsum function, we will calculate the sums of the rows of the matrix.

R

# R program to illustrate
# rowSums() function

# Initializing a matrix
x <- matrix(rep(2:10), 3, 3)

# Printing Matrix
print(x)

# Calling the rowSums() function
rowSums(x)

Output:

     [, 1] [, 2] [, 3]
[1, ]    2    5    8
[2, ]    3    6    9
[3, ]    4    7   10

[1] 15 18 21

Compute the Sum of Rows of a Array in R Programming

We will create one simple array and with the help of rowsum function, we will calculate the sums of the rows of the array.

R

# R program to illustrate
# rowSums function

# Initializing a 3D array
x <- array(1:8, c(2, 2, 2))

# Printing the array
print(x)

# Calling the rowSums() function
rowSums(x, dims = 1)

Output:

,, 1

     [, 1] [, 2]
[1, ]    1    3
[2, ]    2    4,, 2

     [, 1] [, 2]
[1, ]    5    7
[2, ]    6    8

[1] 16 20

Compute the Sum of Rows of a data frame in R Programming

We will create one simple data frame and with the help of rowsum function, we will calculate the sums of the rows of the dataframe.

R

# Create a sample data frame
data <- data.frame(
  ID = c(1, 2, 3),
  Val1 = c(10, 20, 30),
  Val2 = c(5, 15, 25)
)

# Display the original data frame
print(data)

# Calculate the row sums using rowSums()
row_sums <- rowSums(data[, c("Val1", "Val2")])

# Display the data frame with row sums

print(row_sums)

Output:

  ID Val1 Val2
1  1   10    5
2  2   20   15
3  3   30   25

[1] 15 35 55

Use rowSums() with NA Values in Data Frame

Now we create one dataset with missing values and then we use rowsums function to calculate sum of rows of missing values.

R

# Create a sample data frame with missing values
data <- data.frame(
  ID = c(1, 2, 3),
  Val1 = c(10, NA, 30),
  Val2 = c(5, 15, NA)
)

# Display the original data frame with missing values
print("Original Data Frame with Missing Values:")
print(data)

# Calculate the row sums, treating missing values as zero
row_sums <- rowSums(data[, c("Val1", "Val2")], na.rm = TRUE)


# Display the data frame with row sums
row_sums

Output:

  ID Val1 Val2
1  1   10    5
2  2   NA   15
3  3   30   NA

[1] 15 15 30

We use na.rm = TRUE argument in rowSums() is used to treat missing values as zero during the sum calculation.

Use rowSums() with Specific Rows

Now we can create one dataframe and select few specific rows for calculate the sum of the rows using rowSums function.

R

# Create a sample data frame with missing values
data <- data.frame(
  ID = c(1, 2, 3),
  Val1 = c(10, NA, 30),
  Val2 = c(5, 15, NA),
  val3 = c(NA, 20, 5),
  val4 = c(15, 25, NA)
)

# Display the original data frame with missing values
print("Original Data Frame with Missing Values:")
print(data)

# Calculate the row sums, treating missing values as zero
row_sums <- rowSums(data[, c("Val2", "val4")], na.rm = TRUE)

# Display the row sums
print("Row Sums:")
print(row_sums)

Output:

  ID Val1 Val2 val3 val4
1  1   10    5   NA   15
2  2   NA   15   20   25
3  3   30   NA    5   NA

[1] "Row Sums:"
[1] 20 40  0

Here we are select second and forth rows for the calculating sum off the specific rows.