How it works…

The conversion from a matrix to a data frame works simply by assigning column names and then assigning the class property as data.frame. Since a matrix only contains one data type, the resultant data frame also contains only one data type.

The conversion of a data frame to a matrix with heterogeneous data types works a bit differently. First, it converts all columns into higher and more general data types as follows:

• A combination of character and any other data type produces a character vector
• A combination of numeric and logical data type produces a numeric vector
• A combination of complex and numeric or logical data type produces a complex vector

Then, it keeps only one type of data because a matrix is restricted to only one data type. Also, during the conversion, it preserves the column names, which can be accessed by the colnames() function.