Extracting values from matrix by Column names
A row subset matrix can be extracted from the original matrix using a filter for the selected row names. Since a matrix’s elements are accessed in a dual index format, particular row selection can be carried out.
Syntax:
matrix[ vec , ]
Where, vec contains the row names to be fetched
All the columns are retrieved from the data frame. The order of the rows and columns remains unmodified. The rows and column names remain unchanged after extraction. The result returned is a subset of the original matrix. The row names should be a proper subset of the original row names pertaining to matrix.
Example:
R
# declaring matrix mat <- matrix(letters[1:12], ncol = 3) # naming columns colnames(mat) <- c("C1","C2","C3") # naming rows rownames(mat) <- c("R1","R2","R3","R4") print ("Original Matrix") print (mat) # extracting rows row_vec <- c("R2","R4") row_mat <- mat[row_vec ,] print ("Modified Matrix") print (row_mat) |
Output
[1] "Original Matrix" C1 C2 C3 R1 "a" "e" "i" R2 "b" "f" "j" R3 "c" "g" "k" R4 "d" "h" "l" [1] "Modified Matrix" C1 C2 C3 R2 "b" "f" "j" R4 "d" "h" "l"
Extract Values from Matrix by Column and Row Names in R
In this article, we will discuss how to extract values from the matrix by column and row names in R Programming Language.
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