Extract the Submatrix with Column Values Greater than 7 in R

R Programming: Matrix Exercise-7 with Solution

Write a R program to extract the submatrix whose rows have column value > 7 from a given matrix.

Sample Solution:

R Programming Code:

# Define row names for the matrix
row_names = c("row1", "row2", "row3", "row4")

# Define column names for the matrix
col_names = c("col1", "col2", "col3", "col4")

# Create a 4x4 matrix with values from 1 to 16, row-wise, and assign row and column names
M = matrix(c(1:16), nrow = 4, byrow = TRUE, dimnames = list(row_names, col_names))

# Print the original matrix
print("Original Matrix:")
print(M)

# Extract the submatrix where the values in the 3rd column are greater than 7
result = M[M[,3] > 7,]

# Print the new submatrix
print("New submatrix:")
print(result)

Output:

[1] "Original Matrix:"
     col1 col2 col3 col4
row1    1    2    3    4
row2    5    6    7    8
row3    9   10   11   12
row4   13   14   15   16
[1] "New submatrix:"
     col1 col2 col3 col4
row3    9   10   11   12
row4   13   14   15   16                

Explanation:

• Define Row Names:
• row_names = c("row1", "row2", "row3", "row4")
• Creates a vector of row names for the matrix.
• Define Column Names:
• col_names = c("col1", "col2", "col3", "col4")
• Creates a vector of column names for the matrix.
• Create the Matrix:
• M = matrix(c(1:16), nrow = 4, byrow = TRUE, dimnames = list(row_names, col_names))
• Creates a 4x4 matrix with values from 1 to 16.
• nrow = 4 specifies 4 rows.
• byrow = TRUE fills the matrix row-wise.
• dimnames = list(row_names, col_names) assigns row and column names.
• Print the Original Matrix:
• print("Original Matrix:")
• print(M)
• Displays the original matrix with assigned row and column names.
• Extract Submatrix:
• result = M[M[,3] > 7,]
• Filters rows where the value in the 3rd column (M[,3]) is greater than 7.
• M[,3] > 7 creates a logical vector used for subsetting rows.
• Print the New Submatrix:
• print("New submatrix:")
• print(result)
• Displays the extracted submatrix where the 3rd column values are greater than 7.

R Programming Code Editor:

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