How to do it…

The object conversion in R is very intuitive and easy to understand. The name of the function itself tells the story. Let's perform the following steps to convert a matrix to a data frame and a data frame to a matrix:

1. To convert a matrix to a data frame, the as.data.frame() function is enough:

        M1ToData <- as.data.frame(M1)

1. To check whether the newly created object M1ToData is a data frame or not, you can use either the class() function or the str() function. The str() function will give the results along with the type of each column. The output of the str() function is as follows:

        > str(M1ToData)
        'data.frame':       3 obs. of  3 variables:
         $ V1: int  1 4 7
         $ V2: int  2 5 8
         $ V3: int  3 6 9

1. Notice that the columns got new names such as V1, V2, and V3 because a data frame must have a name for each column. If there is no name specified, then the default name will be V1, V2, and so on. To convert a data frame to a matrix, execute the following code snippet:

        D1ToMatrix <- as.matrix(D1)
        > str(D1ToMatrix)
         chr [1:5, 1:2] "1" "3" "2" "4" "5" "Cricket" "Football"     
         "Basketball" "Rugby" "Baseball"
         - attr(*, "dimnames")=List of 2
          ..$ : NULL
          ..$ : chr [1:2] "x1" "x2"

Since one of the columns of the data frame was of character type, the resultant matrix is converted to character type. The resultant matrix is a matrix of five rows and two columns. Since the conversion has been done from a data frame and each column had a name on it, the matrix also contains those column names as follows:

        colnames(D1ToMatrix)
        > colnames(D1ToMatrix)
        [1] "x1" "x2"